righto...
select the CHANGER as source (ie iPod)
by default it'll play the first song on your pod, or the last song you'd selected with the HU.
Press 1, 2 or 3 to select the differant search options:
1 = Playlists
2 = Artist or possibly Track Title
3 = Album
Once you've selected the type of search you want to do, press the search button (little button to the right of the volume dial with a picture of a folder on it).
Use the volume dial to scroll through the list of playlists/artists/albums.
push the volume dial in to select what you want to play.
The track skip buttons will then skip through the tracks on the playlist/by that artist/on the album, but whatever has been selected (say an album) will play on a loop (start to finish) untill you use the search function to choose something else.
Pressing title repeatadly will change what is displayed while a song is playing ie Artist/track/album/playlist name/time etc