First, play the game. They will choose by difficulty first. Once you select,all you need to do is to get an apple and finish it. Use WASD to move. There is a checkpoint. In case you die, you'll spawn where your checkpoint is. Make sure you need to stomp the red goombas just like Mario. The more you play, the more harder it was. On the level editor, type any of these numbers to choose which type you want. Click anywhere to build. There's also a tutorial here, But the size dosen't fit accurately. We highly won't recommended to fullscreen it. Clicking on source sode is recommended. so the costume size may fit accurately. But always prepare the lag. Or else your device will crash.