Here's how to use these:
1: Notice the tab on the bottom of your screen,
labelled BACKPACK
2: Click that tab, and the BACKPACK will open
3: Locate the sprite you wish to save in the sprite list
4: Drag that sprite into your open BACKPACK
5: It may take a few seconds on slower hardware for
the sprite to save in your BACKPACK
6: Do not drag a costume into the BACKPACK! It will
not be saved
Spots Left: 2
Character 1: Tacobell
Character 2: ?
Character 3: ?