The circle in the top right indicates the color. Press e to erase everything. Press space to change the color. Press a to make the pencil bigger, and s to make it smaller. Press f to make it more saturated, and d to make it less. Press j to make it more transparent, and k to make it less. Press l to make it brighter, and o to make it less.
This was actually SUPER easy to make because I just used the pen extension.
