Heads repaired n theres still water gettimg to my oil

I have a 1998 pontiac grand prix v6 3800. Not turbo charged. My dad n I recently bought the car . The previous owner said the heads were busted so we replaced the heads n did sum other random things bc it wouldnt start but now that it will start thr water is still getting into my oil. What do I do now I dont understand. I would appreciate any advice. Thanks!!!!!