Just to clarify Phils comment Mr. Kick, when he says "dump it up against the wall of the firebox closest to the smoke chamber" he does not mean literally "against" the wall with the opening into the smoke box.
He has the firegrate mod like mine, a 20"x16" expanded steel, which pretty much cover the entire firebox so no coals fall down to the bottom.
It really helps to have this entire surface area, as you can put coals close to the opening to start off, then later when you have a coal bed and are maintaining temps, you can add coals to the back near the side door, to have a slower burn, or add coals closer to the smoke box when you need them to light quicker to add heat (can do this with chunks of wood too, just using charcoal in my examples to be consistent with my splaining.)
So back to what Phil said, you never lay coals direct against any of the sides of the firebox. You'll end up getting burn through and shortening the life of the box. So he means, pile a chimney on the fire grate, close to the opening in the smoke chamber side.
As reference, I have the grate on the lowest notch. This allows me to have enough room to reach up into the chamber from the side door to add splits, rather than opening the top and loosing heat (and a fuel wasting way to tend the fire. Get heavy gloves, like welders gloves and reach up in there. I buy these blue leather ones in the Bash Pics section that I gave to everyone. They work great.
"Boots and Pants and Boots and Pants and Boots and Pants..." - Maxwell
Bandera, M-BGE, WSM, Gold Kettle, Kenmore Gasser, 36Qt Turkey Fryer, ECB, Dutch Oven