Yes, well that takes care of the theory but doesn't really explain what to do. The principle is to add as much damping material as you can to reduce standing waves and flutter echoes without reducing the output from the ports (too much). It's a bit of a balancing act, but with the right measuring equipment you can see exactly what effect the damping is having on the system and choose the optimum amount of internal damping. That's how I arrived at the damping layout for the Basschat 12 cab. If you over-damp, you'll reduce port output; if you under-damp, you'll have a lot of ringing going on inside the box.
As a rule of thumb, you should line all the walls but keep the area around the ports clear.