This is in the ROADMAP part of the stickys, up on top of the Q-Talk Thread list. Lots of knowledge crammed in there, so give it a look. Post #10 in here is a layman's writeup:
http://www.bbq-brethren.com/forum/sh...hlight=Turning
It's pretty vague and bland, but it's a start. Look around in the ROADMAP area; there's more good info there than any amount of searching will get you. Read up on Smokey Al Gold's recommendation, too, as that will give you a lot more insight to some specifics.