Is the bathroom finished already?
If there is no tiling yet at the place you will be mounting the screen, then it would be a good idea to fasten a strip of timber to the brickwork to mount the screen to.
If this is, as masona has asked, plasterboard onto brickwork, cut through the plasterboard and mount timber to the brickwork behind, then make good and do your tiling. Then when you come to fit the screen it will screw into the timber directly.
If it is a studwall, check that there isn't a stud there already. If there is a stud, screw the screen directly into this timber. If there isn't, the surest approach would be to install an extra stud where the screen will be (either from the bathroom side of the wall or the other side).
I dotted and dabbed my bathroom, and used the first method I mentioned. It makes it very easy to fit because screwing directly into wood is so easy.