Measure the space for your tub surround with a measuring tape. The height you need is from the bottom of the shower head to the top of the tub. Measure the walls around the tub so your specifications are exact.
Buy a tub surround kit that fits your measurements. You can get them from specialty RV businesses like Tom Raper RV Parts, or you can find them at home improvement stores.
Cut away the wallpaper with the razor blade. Slide it in from the edges and jab at the adhesive holding up the paper. Rip the paper off the wall with your free hand. Repeat this process until all of the wallpaper is removed. If there are little pieces left on the wall, that's OK.
Align your tub surround. Hold it up exactly where you want it to fit and keep the upper side below the shower head so you don't have to do any cutting. Mark the edges of the sides and the top on the wall with a pencil. Pull the tub surround away from the wall, and apply contact cement to the back. Press it against the wall inside your markings and let it dry.
