Add the following to under the <head> tag:
Add the following after </body>
Source for this: http://stackoverflow.com/questions/15231812/random-background-images-css3Edit the default.html.style.min file found in the CSS folder of your storefront server. Comment out the line:
background-image:url(../media/bg_bubbles.jpg);
Add your picutres to C:\inetpub\wwwroot\Citrix\YOURSITE\media\images and label them with [number].jpg
Refresh your storefront page a few times and have rotating wallpapers!
David Rowe