Paneling in the bathroom? Never seen it before, wouldn't advise it either. Putting a wood-based product in a room that's high in humidity will cause you problems. BUT, if you insist, ... Paneling has 'ribs' at 16" on-center which is where you nail to the studs. Cut the pieces to fit and line the rib up with the stud. Glue, then tack it to the studs. Otherwise, the paneling may fall off the wall. The Home Center can tell you the proper nail/tack to use. Make sure you know how much 'material' you have to go through to get to the stud. (1/2" greenboard, at least.) YES, I'd use a latex-based primer/sealer for highly humid rooms. Zinsser is good stuff. Then put up the board.