Create a Drawing
Let's start by creating a tile drawing to place on your map.
From the Draw tab in the dashboard, you can create a new drawing.
New drawing icon
You can also create a new drawing and/or change the canvas size by pressing the icon in the top right corner.
Drawing Tools
Color Palette
Open the color picker by clicking on the color swatch. You can choose from a variety of colors.
Paint Bucket 
Select the paint bucket tool to fill the canvas with the selected color.
Pressing the paint bucket icon will toggle between the paint bucket and brush tools
Brush
Select the color palette again and choose a different color.
I chose to draw some grass to use as ground tiles.
Remember to toggle the paint bucket tool off by clicking on the icon
Save Drawing 
Press the save icon, pick a name for your drawing, and press Save.
Use the dropdown to select the type of drawing you are saving
For now, we will save it as a Tile
Eraser 
Select the eraser tool to erase pixels from the canvas.
Erase Drawing 
Press the trash icon to erase the entire drawing.
This does not delete the drawing but clears the canvas.
Undo 
Press the undo icon to undo the last action.
Redo 
Press the redo icon to redo the last action.
Grid 
Press the grid icon to toggle the grid on and off.