Activate the Import Panel by clicking its icon (that's the little square with the two arrows on the command bar left of the note) or going to Tool > RAW Material Editor and import it as "Panorama". Then you can choose it as a parallax background in the map properties.
Background is the background for battle screens. You can't use it on normal maps then.
Btw, you should post technical questions in the "Technik Forum" (that's German for a forum where technical (Technik) questions belong). It's right below the Community Forum in the overview.
Look here:
http://forum.rpg-ring.com/forum/forumdisplay.php?f=20...