May I suggest reading the already existing howto's for these types of things first:
http://www.ibiblio.org/pub/Linux/doc...AID-HOWTO.html
I don't mean to just pun you off to RTFM but the howto's are quite handy, we shouldn't have to rewrite them here when someone comes along and asks the same general type question.... and so on..
If you read and attempt, run into problems, then ask more detailed questions along the way in setting up your software RAID.