The various categories in LoopWall include animals, nature, food, architecture, and space, among others. Tap one to view the animations it includes. When you find one you like, just tap to edit it.
Editing the GIF you want to use as a background is quite important. The size of each GIF tends to be much smaller than the screen size, so if you don't do a bit of light editing it usually won't fit right. The best option is usually to zoom in until the GIF takes up your whole screen.
LoopWall is quite an original customization app thanks to which you can create a practically infinite number of animated wallpapers.
Requires Android 4.1 or higher.