what to use on joints with tile backer
hey guys, i redid my bathroom and gutted it, Im up to the point where i put fiberglass board up everywhere besides the shower surround, at the shower surround i used tile backer the blue stuff. what do i do as far as my seams on my tile backer in the shower surround. do i just use the mortar? if so what kind is recommended? or is there some special kind of joint compound for the shower surround tile backer? thanks...
p.s. also my floor has the tile backer also, use the same stuff as for the walls?