Start coals 30 minutes before cooking time in a separate place from where you'll be cooking. Continually add briquets or wood to create replacement coals. Arrange the coals under or around the bottom and on top of the flanged lid. There may be up to twice and many coals on top as on the bottom since heat rises. For foods cooked directly in the oven, the bottom coals are placed around the oven to create heat without burning the food.
Experimentation is the key.