Click on the circles to change color. Press b for black (Why? Because I wanted one row of colors and I couldn't fit black in there). Press the erase button to erase your whole drawing. Use the size slider to make the lines (once you draw) bigger or smaller. And the "COLOR" variable tells you what color you're going to draw, hence the name.
Thanks to rehanscratch's YouTube account for the tutorial on how to make this project. P.S. rehanscratch's YouTube account is SL SMART MIND