This is a Live Wallpaper, so, here's what you have to do to install it:
STEP 1. Tap and hold
Press the home button to first go to the homescreen. On the homescreen, just tap and hold on any blank spot until a context menu appears.
STEP 2. Tap on “Wallpaper” and then “Live Wallpaper”
In the menu or dialog box that showed up in STEP 1, just tap on the “Wallpaper” option, and then the “Live Wallpaper” menu item.
STEP 3. Select Bloody Birds Live Wallpaper
STEP 4. Tap "Set Wallpaper" to set it or "Settings" to configure it
This free app is ad supported and may contain ads in the notification tray and/or home screen.
Aurora Borealis Live Wallpaper