Picture Change on Refresh

Hello Guys…
I need some codes to change picture on refresh in an .SWF file. I tried searching it in several forums but didn’t find the solution. I’m explaining what I want actually…

www.empirevogue.com

This is the site i’ve done. See the background picture (girl). It’s in the flash file. I want the same transaction on the picture but on refresh I need this picture to be changed. I want to use 20 pictures. Could u guys help me out???