Kies provides instructions including explaining that you need to remove the battery, hold a certain button and all that good stuff. I have done it and it was a major pita the first time around. From what i've read which seems to be true is that you should never do firmware updates from the front USB ports (read about this on XDA) on your system. Nor will recovery work on those ports and for what reason i'm not sure. But for me using the front ports kept causing the update to fail on me again and again.
So the best thing to do is take it to your local AT&T store and let them do it for you.