arrows or WASD for movement press zero to enter level editor mode. Press 1, 2, 3, and 4 multiple times to cycle through all blocks. Press E to edit using the block that your mouse was on when you pressed E. Click on blocks to erase them. while in Editor mode you can not press L to go to a different stage and r to change the bouding box it will save when you press the green flag again, but not when you reload
from griffpatch's youtube tutorial
