You can click y to change color or slide the slider and click s to higher the pen size or slide the slider and press l(not capital i) to lower the pen size or slide the slider. Click the trash can to erase the whole screen. The paint dot on the top left corner of your screen indicates what color and what size the pen is. *UPDATE* Trash can fixed (thanks for people who sold me when i tested it worked)
Thanks ronnoc578 I wanted to help you with the project a little bit. @ronnoc578