Press up to send the square up, press left and right to move, and try to touch the green, but not the gray. Press M to go to the menu and if you want to save, you get a code that you can enter next time you play (press L on the first menu.)
This was meant to test out my new saving system. This doesn't check if your code is invalid, so try not to put in invalid codes. If you want a code with all levels unlocked, then it's jfbgsss_t_70 I do recommend beating it yourself first.