Patching and Plastering - Drywall help

I am looking for advice on how to install new drywall to existing. I recently replaced an old tub and surround 1 piece with a new 2 piece surround. Now I have about 18" around the surround to replace and a corner also. The existing wall has texture on it. Any information will be greatly appreciated.

Welcome to the forums

First you need to nail/screw new drywall to the affected areas. If it butts up [same wall] to the existing drywall you need to use the same thickness of drywall - most likely 1/2" could be 3/8" or 5/8"

Where to pieces join together you need to use drywall tape and joint compound to seal the gap. If there are any outside corners involved they will need corner bead [metal or vinyl] After the tape/mud is dry you need to add 1-2 more coats of mud, sand as needed to get it ready for texture.

There are different types of texture, the 2 most common are orange peel and knockdown. Although these are originallly sprayed on they can usually be duplicated [with thin joint mud] on small repairs with a sponge or brush.

Mark - why the need to use the same DW thickness? Why not put 3/8" over 1/2" or 1/2" over 5/8"? The only thing I would do different is to use a longer screw. Probably 1 5/8" instead of 1 1 /4".

Sorry, I misunderstood. I thought you were butting up to drywall and didn't realize you laminating over it. Any size rock will work. I would use 1.75" or 2" drywall screws.