Green board from the nailing flange to the ceiling. Finish it with tape and mud then paint. Or if you want to tile up to the ceiling then cement backerboard from the nailing flange to the ceiling then tile on top of that.
Thank you very much! I have put up greenboard and painted but what do I do about where the tub surround ends, it's just a straight cut and then painted wall? Don't I need something to make it look more finished?