I already have a toilet and drain system in the bacement and I want to add a shower, all the drain pipes are on top of the floor about 1" off the floor what do I do to tap into that drain, can I use it or not

Little tricky to add a shower since the drain pipe is above the floor level. You will need a trap so that makes it even higher. If you build a platform, probably 6-7" high and put the shower pan on that it would probably work.