First, be sure to click the green flag to ensure everything works properly! Then, you use the arrow keys to scroll through the pages (aka backdrops). (Right arrow for next, and left arrow for previous.)
I made this all on my own! Though all rights to these characters go to Ninja Kiwi! And hey, if you liked this, check out episode 2! Link: https://scratch.mit.edu/projects/1368625255