go to the game store studio (currently not open), pick out a game cartridge, and put it inside the project. if you would like to make your own game, the cartridge template is inside this project. a cartridge can have up to 5 sprites. so a game for this system can't be over 5 sprites.
A lot of things are still being worked on. for now just make a game with the cartridge template and try it out on here. this will definitely be updated. also don't worry about Five Nights at Mushy's. It's almost done ;)