German engines are notoriously more complicated than they look, I would suggest taking it to a qualified mechanic that specializes in german cars.  If you're dead set on doing it yourself Hanes and Chiltons make great manuals that show you step by step how to practically dismantle the entire car and rebuild from the ground up.  You probably ought to take it to a machine shop to make sure that when the head went bad it didnt warp or distort the plate it rests on, installing a new head on a warped engine surface would be a costly mistake you'd end up having to fix twice.