Just follow the instructions at the bottom of the screen.
Thanks to Scratch for the sounds. (I don't quite have them working yet.) I only have levels up to level 9, but I'm going to add more eventually. If you get to the portal on level 9, the level counter in the corner of the screen just keeps going on towards infinity. This project is dedicated to @Codephile, because he's been bugging me to get back into Scratch. Thanks @Codephile!