Im going to remove two windows on the side of my garage that have rotten frames around them, then cover them up by placing vinyl siding. I've found plenty of DIY videos on removing the old frames, but im unsure how to "frame" them back in so that I can proceed with the siding. Maybe Im using the wrong terms. Any point in the right direction would be awesome. Thanks.

 

Once the windows are removed, you will be left with a "rough opening" where your sheathing is flush with the studs. Best way to fill that in is to plan on installing more 2x4's around the entire perimeter. Then you will need to add studs vertically, it really doesn't matter exactly where, although most carpenters would probably try to match the layout on the rest of the existing part of the wall by finding the studs on either side of the window and matching the layout that was started originally. Generally you want those studs 16" on center so that if there is a seam in the plywood, that plywood seam will fall in the middle of a stud. You will use whatever thickness of plywood it takes to bring the sheathing out flush with the existing. On older houses, that's most often 3/4".

If you have 1/2" plywood laying around, you can use that too, just add a 1/4" shim onto the outside of your studs, then put the plywood on top.

Cover the wall with a WRB (housewrap or felt paper) prior to installing your siding.