Finally you reach this brown hut/office, which is where you can register and pay for camping any time day or night. They will give you a copy of the 14X-Day flyer, which will explain how to pay the Church after 1 PM the next morning, and where. Wisteria camping fees ($10/night) and X-Day attendance ($30/week) are completely seperate. You can get your SubGenius wristband down the hill where the action is happening in the daytime, after selecting your camp spot.
The campground is very large and some people will want quiet, whereas others will want electricity. It's kind of hard to have both due to the distances involved. Campers are welcome to bring generators, as long as they are not venting their exhausts into neighboring tents. Unless there is terrible rain, turning the roads into quicksand-like muck, you can park where you camp, and drive (slowly) from place to place.
Campsites are numbered, so after you pick yours you can reserve others for late-arriving friends and tell them your campsite number.