need help to mirror 2 drives

hello it experts!

I recently added a pci raid card to my pc to mirror two 80 gig hard drives. I am new at this, can someone explain the setup or guide me where i can find an easy illustration for this (a setup shown w/ pictures would be nice). My current OS is Win XP Pro SP/2. So I DO NOT want to mess this up since I got alot of important files currently on hard drive.