rockyou.com is giving me fits right now but sign into your rockyou account. Click on "edit" underneath the slideshow you want. Under the "Customize" section, the first tab is music. Click on it.
From there, I'm trying to add music to a slideshow of mine so I can give you step by step instructions but this site is absolutely acting up. So, for me there was an option to play music or add music. I added a song and I'm guessing that if you go into yours the music will be there but instead of the add option it would be to delete. But I can't say since I can't do it.
I'll keep trying and if I get it I'll come back and fill you in. I hope this helps so far though!
at 3:23 PM on Mar. 22, 2009