To create a 3-zone fire, mound the embers double thick on one side of the grill for your hot or searing zone, in a single layer in the center for your moderate or cooking zone, and leave the remaining third of the grill clear for your cool or "safety" zone.

A watchpoint here: Wood burns more quickly than charcoal, so you'll need to replenish the embers more often. I keep a brisk fire going on one side of the grill and rake the embers to the other side where I do the actual cooking.