Got it. They usually provide some basic information a couple of days before the festival, but it will probably be similar to the info from the last edition (http://haldernpop.com/36-haldern-pop-fe ... len-infos/
In general, there are three areas:
a) The festival ground with the Mainstage, Spiegeltent and Niederrhein-tent
b) The camping ground, which is right next to the festival ground and provides plenty of space. The rules are very liberal, you can even park your car next to your tent and bring bottles and stuff. Nevertheless, people are very careful to take their garbage away again etc. On the camping ground there is also the Tonstudio, which hosts some shows on Saturday
c) The village with the Church, the Pop Bar and the Market Stage. It is a 15-20min walk from the festival ground.
In the TimeSquare App you may find a festival map.
Hope this helps for a first overview.