Need help with a weird javascript random image generator

Hey Everyone!

I was wondering how to make a random image generator in javascript that pulls 2 linked images. For example, I have 3 sets of 2 images.

set 1
sunset-top.gif
sunset-bot.gif

set 2
frog-top.gif
frog-bot.gif

set3
soup-top.gif
soup-bot.gif

I want the random image generator to randomize between the sets.And then be able to define where each image is placed on the page.

I really have no idea where to start. It should be really simple, I’m just not to good at javascript. Thanks a bunch to anyone who help out!