Are you referring to the Chargriller Smokin Pro? It looks like that's the only one with an offset firebox. When I had my NBSS, I found I got the best results by first cleaning out any ash, leaving the bottom grate in place, closing the door and vent all the way, pouring in as much Kinsford as it could hold, throwing a few hot coals on top, and closing the door. Leave the exhause open. The gaps around the door provided just enough air for a Minion method and it burned for a while, fairly even temps.
dmp