It is live wallpaper so you can't open the app, you will need to follow the instruction below in order to set the wallpaper.

Also slower/older devices (shipped with Android OS below 2.1) can't run it too, currently it has been tested on Nexus S, HTC Desire and Samsung tab so any mobile devices that is equivalent to them should run fine.

Instruction:

Home -> Menu -> Wallpapers -> Live Wallpapers

If you have put the app on SD card and restarted the phone, the wallpaper will reset to default since the system couldn't find the app first.