1. Install all piping before installing the tub itself.
2. Lower the tub into place so that the continuous flange fits against the wall studs and rests on 1 x 4 or 2 x 4 supports. Anchor the tub to the enclosure with nails or screws inserted through the flanges into the studs.
3. Assemble the drain connections by connecting the tub overflow with the tub drain Above the trap, not beyond it. The trap will have a compression fitting that screws over the arm of the overflow assembly.
4. Hot and cold water lines are run to the tub/shower mixing valve where they are attached, usually by, sweating these directly into the hot and cold ports of the mixing valve.
5. Run a pipe up the wall for the shower head. On the top of this pipe, sweat on a brass female threaded winged fitting that is nailed or screwed into a framing support.
6. Extend a piece of 1/2" pipe, according to the manufacturer's instructions, for the tub spout. Sweat on a male threaded fitting at the end of the pipe or use a brass nipple of the proper length and a 1/2" cap.
7. At this time you will need to have your rough plumbing inspected.
8. Restore water pressure and check the drain connection and the supply pipes for any leaks.
9. Replace the wall with moisture resistant drywall as a base for your wall covering. Seal joints between the wall and your new tub with silicone caulk as protection against water seepage.
10. Install the Spout, handles and shower head. The shower head screws onto the shower arm stub out. Whether installing a new shower head or replacing an old one, always clean the pipe threads and apply new pipe joint compound, PTFE tape or both to prevent leaks.  

Bath Tub Refinishing
Resurfacing and refinishing a bath tub requires trained craftsmen. The professional refinishers will give your old bath tub an upgrade by ridding it of unsightly stains, scratches, dents and leaks and giving it a totally new appearance. Bath tub restoration also involves removal and reinstallation of drains. The tub and tile joints must be re-caulked and the chrome fixtures must be cleaned. The process of bathtub restoration involves scraping and washing the surface and applying a solvent.
The surface of the bathtub is then etched and neutralized and sandpapered. The special chemical that is used by professional refinishing companies is Aliphatic Acrylic Polyurethane Enamel. Reglazing and restoring the bathtub will improve its longevity as well as enhance the appearance of the bathroom. If your bathtub is in need of extensive repair work, it might be worthwhile to replace it with a new one. Regaling and restoring the bath tub can be done in a matter of a day at most and therefore you are saved the inconvenience. This job is done by trained craftsmen who are skilled in restoring and refurbishing old bath tubs and other surfaces.
Bath Tub Liner
Another alternative to replacement of an old bathtub is to use bath tub liners. Bath tub liners come in a variety of colors and resist chipping and scratches. They are custom made to fit over your old and worn out bath tub. An estimator will identify your existing tub and take precise measurements. The new bath tub liner is installed over the existing tub. In a matter of a few hours, you will have a bath tub that is good as new. The rest of the bathroom remains undisturbed. You are saved the costly replacements to walls, flooring and plumbing.
Acrylic bath tub liners are lustrous and glossy and come in a wide range of colors and can be matched with your existing tiles and flooring. With a life expectancy of nearly 20 years, it is little wonder that acrylic bath tub liners are a popular choice for bathtub restoration. Liners with molded slip resistant bottoms provide additional safety. High gloss surface of bath tub liners gives your bathroom a totally new look. Regular cleaning with mild soap solution and soft wash cloth is all the maintenance that is needed. Care should be taken to see that there is no gap between the tub and liner so that water does not accumulate in the crevice.