Welcome. BM has its own special ways of doing things.
First you can join a camp that is placed within specific boundaries beforehand. If you are with them, you just go to their location and follow whatever camp instructions there are. Here is a 2011 map of preplaced areas from last year:http://www.burningman.com/preparation/maps/11_maps/
Preplaced areas are dense.
If your posse is solo, you can camp anywhere there is room after the public gate opening. Good to check with neighboring camps before setting up. But in the middle of the night or day you could get some new neighbors with generators, exhaust or a sound system. If you look st the sat photos, you can see that the closer in, the denser people camp.http://gigapan.org/gigapans/66285/
If you really want room, camp outside the ring road, or in the walk in camp area if that works for you. Walk in is no vehicles. Also possible to camp deep playa, but more complicated. Outside the ring road otherwise, whatever.