In one of your homescreens, tap menu key -> Wallpapers -> Live wallpapers
This is the free version, paid version offers the following additional features:
* tilt your device to change rotation direction
* use your own textures, e.g. a panorama from your personal world or your favourite servers world (tutorial: http://netz-weh.de/wordpress/?p=401)
* experimental blur effect
* experimental mirroring upper half of your custom texture, to use normal panorama textures instead of skybox textures
* no "Lite" watermark
https://market.android.com/details?id=de.netzweh.minelivewp