There is small fire pit in my back yard that is just the perfect size for my dutch oven. It is the perfect size, because I dug it that way. Here you can see the charcoal being prepared. It is important to make sure that the charcoal is well lit and burning or you can experience temperature control problem once you start cooking.
Notice how I placed some of the charcoal on top of the dutch oven as well. This is to help the oven heat evenly. Even heating is a key element in successful dutch oven cooking. Nothing is worse than food that is overcooked on the bottom and raw on top. The temperature can be controlled by the number of charcoals used. If you want more heat on bottom, then put more charcoal underneath. Each charcoal briquette will produce approximately 10 - 20 degrees. SO if you want to cook something at around 325 degrees, then you will need approximately 20 - 25 coals. These temperature will go up or down according to the size of your oven. A larger oven will need more coals and a smaller one less.
Now it is time to sit back and enjoy the fruits of your labor.