XML Help!

Okay i have done the tutorial with external pictures being read from an XML Document.

http://www.kirupa.com/developer/mx2004/xml_flash_photogallery.htm

My question is I want to have thumb nails at the bottom of the page that when clicked will fade in the new picture like when you click the next or previous button. I am going to have images that can be either movie clips or buttons. but i would really like some help on this one.

Thanks