There are now three sets of background tiles to choose from. Set "0" is the default we've always had and can not be changed. Set 1 and 2 are your own personal sprites to customize. Click the Editor button to go to the sprite editor room. Click on the Tile Set 1 or 2, then click on the tile you want to edit. Click the "Save" button when you are done to save all your changes to all the tiles.

12 custom images should be enough for anyone!

(Sorry about the long delay, but this required some major changes behind-the-scenes. Next up is custom items)