1991 Camaro RS T-tops ...
i have some bubles in the fabric that looks like it has stretched and kinda fallen little. I am wondering how i go by fixing this and what i need to do.

That is the first sign the fabric is seperating from the foam underlayment. The foam underlayment is then glued to a cardboard backer that fits into the roof of the car. The cheap and very temporary fix is to try to "inject" some adhesive into the bubbles and seal them down. The proper fix is a new headliner. The headliner is removed from the car, fabric and foam removed from the cardboard, and new fabric and foam applied. Don't damage the cardboard backer.

where can i get the fabric to do this

Check classicindustries.com for full headliners. I thought I saw them there.

Also, check the forums at http://www.thirdgen.org/

It is a little difficult to make them (I tired with moderate success at best). There are a lot of exposed corners.