Hold your mouse down and drag it around to start drawing. You can change the color of the pen by the rgb variables and the size of the pen by the pen size. The dot on the top-right corner shows what color you are currently using. Click the Hide Variables button to hide the variables. Click the Show Variables button to show the variables. Here are some base colors to use: Red- r-255 g and b are at zero Orange- r-255 g-128 b-0 Yellow- r-255 g-255 b-0 Lime Green- g-255 r and b are at zero Dark Green- g-128 r and b are at zero Cyan- r-0 g-255 b-255 Blue- b-255 r and g are at zero Purple- r-128 g-0 b-255 Magenta- r-255 g-0 b-255 Black- All of them are at zero White- All of them are at 255 Gray- All of them are at 128 Brown- Keep b at a low level and change the r and g so that g is a bit less than r. Of course, you don't need to use these exact colors. You can experiment and find more, too! To erase, just cover the desired area with white.
I used a little bit of code from @griffpatch's tutorial on color scanning. The rest is by me.
