Summarize the following:
Choose an adhesive designed specifically for tub surrounds, which comes in a tube. Cut the tip off the tube and load it into a caulk gun. Press the gun’s trigger to spread the adhesive in a zigzag pattern, then smooth it out into a thin, even layer with a trowel. The adhesive sets quickly. If your surround comes in multiple pieces, focus on installing 1 section at a time. Spread more adhesive once you finish installing the first panel. Lift up the surround and fit it against the wall according to the guidelines you marked. Make sure it is flush against the wall. If your surround comes in sections, apply each panel individually, fitting them together. The easiest way to install panels is usually by starting with the side panels. Place the back panel next, then finish with the corner panels. Fit new accessories you purchased or return old pieces you had to remove during the installation process. Place the accessories according to your bathroom and its unique layout. Some faucets, for instance, fit on a backplate you fit to the wall first. Others attach directly to bathtubs or a pipe on the floor.  For specialty accessories like grip bars and soap holders, you may need to drill holes in the surround. Screw the accessory brackets to support beams behind the surround to prevent them from coming loose. To find the support beams, use a wall stud finder. If the holes you make in the surround are too big, the accessories won’t fit properly. You can fill in small gaps with caulk. If the gaps are so big the accessories don’t fit tightly against the wall, you may need to start over with a new surround. Leave the surround alone until it adheres properly to the wall. When you come back to work on the tub the next day, make sure the panels feel impossible to remove. If they wiggle at all, they aren’t properly bonded to the wall. Apply more adhesive to stick them in place. If the surround is loose, water may seep behind it or it may fall down, which can cause a lot of damage. Get a bottle of waterproof silicone caulk and load it into a caulk gun. Cut the tip off and press the trigger to shoot caulk directly into any spaces that need to be filled. Then, after letting the caulk dry for 24 hours, turn on the water supply to enjoy your new surround.  You will need to squeeze a bead of caulk between the tub and the bottom of the surround. If your surround came in panels, also put caulk between each panel. While you have caulk available, spread a bead of caulk underneath fixtures like the faucet escutcheon to waterproof it.

Summary:
Use a caulk gun and trowel to spread an adhesive over the wall. Press the tub surround flat against the wall. Finish installing the tub’s faucet and other accessories. Let the adhesive dry for 24 hours before continuing. Seal cracks in the surround and accessories with caulk.