Use the coloured/colored buttons on the left to change the colour/color use the arrows on the bottom left to change the pen size, the red button of the top right corner clears the screen, the right one erases things (white paint) S will create a square press space to confirm it D will create a filled in square press space to confirm it L will create a line press Space to confirm position and it will appear!
Just a stupid little thing i spun up have a go!
