|---------------------| INSTRUCTIONS |---------------------| No. 1 - Click the "Remix" button on the upright corner. It's a green button with a swirl. No. 2 - Rename your project to whatever you'd like. No. 3 - Click the "Backdrops" button. It has a paintbrush. No. 4 - Edit the cartridges in any way you'd like!
Thanks to @OS2GameDeveloper for the original project (32X) Design Game Cartridges.