just getting into smokers and bought this one, 1) anybody have one and how is it, 2) it has two air doors on the firebox one I know is for air for the fire ( it is below the wood rack, and the other is above the wood rack about even where you could grill in the fire box. I had a hard time the first time using this can anyone tell me if the top door should be open during smoking or completely closed, I think the bottom one controls air for fire which will control temperature