Use mouse. (use a mouse and not the pad on your laptop) - change setting by clicking on the space key. Drag different colors form the top bar. Drag bricks into the grey bar at the top to delete them. When you let go of the bricks they fall until they are touching the ground or another brick
[HIGHLY RECOMMEND RUNNING ON TURBOWARP) https://turbowarp.org/600814656 all me, @RandomLord