You may want to search for "headliner" in the search tool. Basically, you remove the old headliner board, remove fabric, glue on new fabric (available from Joann's) and put board back up.
What jaskispyder said is correct. I did this on my 88GT and it came out beautiful. If your backing board is disintegrated though you may want to replace it with a new one. TFS has them. In most cases though the backing board is still sound so you just recover it.
Isn't it strange that after a bombing, everyone blames the bomber, his upbringing, his environment, his culture, his mental state but … after a shooting, the problem is the gun?
Take your time, do it right, and avoid problems in the future.
I did my own headliner, but I used fiberglass and resin to reinforce the backing board. One thing I recommend, is to use 3M spray adhesive to glue the fabric on to the board. Spray the backing board and the fabric lightly, but many coats to be sure to cover all areas that will glued down. BUT, before you glue, be sure ALL loose material is off the backing board. I missed a small area, and I have a sag, it isn't bad, and most people don't notice it, but it drives me nutz...
The glue is a contact type glue, once it touches, it is stuck. Have a friend help you apply the fabric to the backing board. If you try to pull it off, it will tear the foam off the fabric.
Replacing the headliner is one task that really makes the interior look so much better! Now, if I could sew, I could do my own visors...