Check out the *** **** FAQ, specifically Construction Systems. Under that, you'll see a short reference about 'Removing a load bearing wall'. It's not much but a good start.
Another quick reference can be found at Wall Projects. My best to ya and hope this helps.
Jay J -Moderator
PS: A good tip is to put the material for your header RIGHT WHERE THE CURREN WALL IS so that when you build around it, you won't find out the hard way that you can't get the material IN BETWEEN the temporary walls! (Hopefully, you know what I mean ...)