Question

THis is directed to you internet know-it-alls out there(JEremy, I'm looking at you). I am looking for the ability to randomize a picture on my blog. I have spent the last hour searching and cannot find anything that I can use. I want to randomize the top banner..I have two pictures so far but I want to make more. If anyone knows how please let me know. By what I've seen it's pretty complicated though.