These step-by-step instructions summarize my weeks of learning how to draw a map. Follow the steps in order. You will need an image for the game on the game page. I also used a pre-written script that contains a dungeon map, and text describing each room, complete with NPCs and monsters. I highly recommend that you don't create your dungeon without some up-front planning.

I also create a pristine version of the dungeon map, then make a full copy of it for play (add player characters and you're ready to go). That way I always have a fresh unspoiled dungeon for playing it again. I prefix the title with "Tpl_" and the tag "template" to designate my original.

Create the Game Sandbox

1. From the Roll20 Home page, click the Create New Game button beneath the banner.
2. Enter the name of the game, and any search tags you want to go with it. I have a lot of maps, so I put "template" if it is the original, the game type (Chronos), and the author(s) because sometimes I use published material.
3. Leave the Character Sheet as None for Chronos, and the module as None.
4. When you click the button OK, I’m Ready. Create Game, you are taken into an empty page (Create New Page) of the game. We’ll come back to this. Use the cog menu to Exit Game.

Enter Game Image and Description

1. From the Game Page, you should see the game name, with the default image: a d20 icon.
2. Ignore the Playing test field below the image. Click on the image and upload your own image for the game.
3. Enter a description of the dungeon (or cut-n-paste from an external file, e.g a Word doc). I have a pre-written script that I use to follow along with the Party as they go through the adventure. Enter the title of the game in the subject area, and the first line of the description should say something like "A Chronos Game for Adventurer Level 2 – 4."

Configure the Map Page

1. Join game to enter into the mapping area. Select the page icon in the top right (overlays the map, not part of the top-right main menu.
2. You should see a Create New Page and a Start page, with the Players banner over the latter. Hover over the Start page and choose the cog wheel icon that appears to configure the page.
3. The page size defaults to 25 x 25. Set it to the dimensions of your map. You can make changes to this later if your map gets too large. Make sure that the Scale is 1 unit = 5’. Leave all the other options untouched for now. The drawing tools use the grid, so your grid should be on, which it is by default. Save changes with the OK button.
4. Click on the page title at the bottom of the page icon to change it (instead of Untitled). Rename the page. Mine is often called Upper Level, or Main Level. (Later, you will make a landing page for Characters to start on without having them start in the map itself.) Return to the grid page.

Draw the Map Outline

1. Use the Magnifying Glass to change the view to say, 70%. You should see the top left corner of the page.
2. Using the left menu, click on the cube (layer tool) to get the Map Background layer (looks like a teardrop). Unlike the token and GM layer, the Map layer is the most stable, and probably will never change during the game. The other layer is the Dynamic Lighting layer, and is also very stable. These other layers are discussed later.
3. Click on the brush icon (drawing tool) and select polygon/line option to draw lines. A color palette will pop up with black ink (default) and Regular size. (The foreground color is on the left; the background color is on the right. It should be set to the checkered pattern, meaning it is transparent.) The mouse is now ready to draw the map outline.
4. Hold the Shift key down and click the mouse to draw from where it currently points. Each time you right click, the line will draw to the closest grid intersection of the mouse position. Let up on the Shift key if you don’t want it to lock onto the grid. A left click will end the line and a right click will begin a new one at a new location, e.g., for jumping across hallways, or to start a new room. If you make a mistake, Ctrl-Z will undo the last line segment. Whenever you click on the polygon/line tool, a small popup will remind you of these keys. Draw an outline of each room of the map at the map layer.

Add Doors as Reference Points

1. It is easy to get confused as to where you are, so add Doors to the map at the appropriate places. Go to the Art icon of the right menu (looks like two paintings) and Search for Maps, Tiles, Textures. Find the image you want for a normal Door and drag it onto the map page. (It will automatically go into your Art Library for easy selection later. The image is marked as a star.)
2. The door is a token, but because you are in the Map layer, it will also be in Map layer. Click on the door icon and select Layer from the dropdown menu. It will move the Door to the Token layer. However, since you are in the Map layer, you will not be able to select or manipulate it. Click the Map (teardrop) icon in left menu and select the Token layer. You can now work with the door token.
3. Resize the door if necessary by selecting and moving the corner handles. Copy and paste the door to wherever there should be normal doors. The door needs to straddle the line between inside and outside the room so that it can be “seen” from either side. Sometimes doors straddle grid lines (across two cells), and sometimes it is more convenient for them to line up with a cell of the grid. Hold the Alt key down if you don’t want the image to lock to the grid.
4. Secret Doors: There is a secret door icon—an S with a line through it. (There are also icons with arrows through the S to show one-way secret doors.) You can place that over the door to show that it is secret. Be sure to place it on the GM layer, else the players will see it immediately. After they find it, move the S to the token layer.

Add Floor Tiling and Room Furnishings

1. For each room, one at a time, populate the floor at the Map layer and furnishings at the Token level. I like to use standard flat tiles for hallways, and interesting tiling for rooms. Who knows what clues might be indicated by an intricate floor layout?
2. For tiling: Return to the Map layer to set down floor tiling: stone, wood, sawdust, straw, etc. Select the your desired tiling from the Art Library in the right-hand menu. You can cut and paste it throughout the room. Use a doubling technique for long hallways and large rooms (copy 1 and paste; copy both and paste; copy all four tiles and paste, etc.
3. If you need part of a tile, you can either resize it appropriately, which sometimes makes it look unfitting, or you can overlap the tiles. There is a To Front and To Back option for each the tile when it is selected; you will usually need to send the tile to the back when you lay it so it doesn’t cover your doors or room outlines.
4. You may also need to place a set of stairs somewhere. Chose the appropriate stair tile from the Art Library and place that instead of a flat floor tile.
5. For furnishings: Move to the token layer and then select beds, desk, chests, whatever you need to populate each room, from the Art Library. For each item you drag-and-drop to the map, a copy will move to your own Art Library. You can access that by selecting the Star icon in the art menu.
6. Discovered Items: Sometimes an item is discovered, say lying in cabinet, or under a bed. Populate these items to, but put them into the GM layer. They are visible to you, but not the players. When the Party discovers the item, push them into the Token layer for the players to see. Voila! For actual play, the items don’t really have to be in the container—placing them in view is sufficient.
7. Room numbers: It is useful to place the room number somewhere in the room on the Map layer. It should be easily seen by the players, but out of the way. In my dungeons, I look up special properties of items by where they were found. The gold ring found in Room 4 may be different than the gold ring found in Room 11. Let it be up to the players to keep track of which room the item was found in.

Add Dynamic Lighting

This is about a Roll20 feature exclusive to Plus & Pro-subscribers, or to players in a Game created by a Plus/Pro-subscriber. If you'd like to use this feature, consider upgrading your account.

1. Lighting is easy to do, but a bit tricky. Reconfigure the page for lighting and set a light source to check your progress. Configure the page by selecting the cog menu for the page in the page menu above the map. On the Page Settings popup, check the boxes near Dynamic Lighting labeled Enabled, Enforce Line of Sight, and Restrict Movement. Now light will not go past the light lines you set up as visibility barriers, but character token also will not be able to pass. This means the characters token will not be able to walk through walls. When your return to the map, you will notice that it is much darker. (You can set the GM Opaque slider in the Page Settings to adjust the brightness.)
2. Set a light source. Pick a torch image token and drag it onto the map. Double-click it and on the Advanced tab and check the All Players See Light and Have Sight checkboxes. In the fields above, set the Emits Light field to 30 and 15. After a lot of experimenting, I think these are the two most realistic parameters. It means the torch sheds light for 30’ but dims are 15’, giving a fading glow to the torch.
3. Select the dynamic light drawing tool. Go to the Dynamic Lighting layer in the left menu (a flame icon) and then select the polygon/line too again, as you did drawing the floor plan. This time select a Small line, and Yellow color from the color palette. (The foreground color is on the left; the background color is on the right. It should be set to the checkered pattern, meaning it is transparent.)
4. Trace the outline of the rooms, hallways, and other areas of the rooms, pretty much everywhere you drew the black borders before but do not draw a line across the doors. Once the line is connected to make a closed area, it cannot be changed. Leave gaps everywhere that a door or other opening appears. If a pixel or two of light sneaks through, you can select the line and adjust it until it is light-tight.
5. Shadow tall items. You also want to draw a light barrier across tall items like bookshelves, so light doesn’t go through, but leaves a shadow on the other side. Draw inside cabinets in case a character walks inside, light won’t shine out except through the door. Don’t draw the light line on the surface of the item though; draw the line within the item’s image to leave enough of the it showing so the characters can see it.
6. Draw in the doors. Use a Small Orange line to draw across doors. During the game, you can rotate the door to open it, and move the orange line to allow light and the characters through the doorway. Move your light source around to ensure that there are no light gaps. If one pixel of light can make it through, then your character tokens can wen their way through too, making it again like walking through walls. You might want to bring the magnification up to 100% or more to check this more easily.
7. Last check: Walk all the hallways and rooms with your lit torch and check for light shining where it shouldn’t. Be especially careful around doors. My frequent error is drawing a light barrier over a door, so the characters (and light) can’t get through it after I “open” the door.

Add Monsters (Mooks) and NPCs

Main Page: Managing your Monsters

Wandering Monsters

Make tokens for all the WMs and place them on the board, but slightly off the map. They may be NPCs or mooks, but you don’t want to spend the time setting up the attributes and other details when an encounter is imminent. If they are off the map, they can even be at the token level; all the easier to drag their tokens onto the encounter location when needed. If they are mooks, only one of each needs to be made; the others can be brought on through repeated cut-and-paste because they will all have the same values.