This is a drawing thing where you basically just draw. To change the color, press the numbers 1-8 and for the eraser click on 9. To make the brush size bigger or smaller, use the up and down arrow keys.
Also the black dot on the right top corner is to see how big your rush is. Oh yeah, and when you're done drawing and if you wanna take a screenshot press h to hide the brush and the black dot to show it again press S. You can suggest more things for me to add in the comments! :D Happy drawing! ^w^ YEET