want to redo rear seats

If you remove the bottom seat there should be a couple of brackets/screws that come out of the bottom of vertical seat, once you remove those screws just lift up on the seat and it should come out.

Its really easy to recover a rear seat but I have never found a store that sells them separately. They usually sell either the fronts only or the whole set. They don't sell the foam for the rear seat either but it is easy to buy upholstery foam and cut/shave and glue it over the old foam. But, usually those back seats don't see a lot of abuse since they are so small and I have never had to add any foam on the several that I have recovered. The procedure is simple...There are hog rings holding the seat covers to the frame. Just lay the new covers in the sun for a while to get them nice and pliable, stretch them over the foam and use hog ring pliers to crimp new rings through the seat covers and onto the frame. The front seats are a little more involved due to wire rods that pull the seams into the frame, but since you are only doing the rear that would be no problem. If you buy the set then one day if you need to replace the front covers you will already have them.