Cute 
So let’s start by talking about how to draw lines (suposing it’s the brush), did you have tryed something or do I have to try to code a little script ? It will be a testing of the drawing features
After that we can move on talking about the shapes to color guessing that the color picker like the brushs in the video are just tweens with the image corresponding to the color one want to use and if you click one of them it will change a variable named brushColour for example