This is the official park campground, with a great location not far from the dune field. There are 88 sites here, but be warned: it is very popular and regularly fills up from mid-May through August. Half of the sites are available on a first-come, first-served basis (open year-round), the other 44 (open May to mid-November) can be reserved online.
Reserve as far in advance as possible; otherwise show up early and cross your fingers. Water and toilets are available.