Installing fromt and rear window trim

Ok I've recently had my car painted(by a friend) and the guys removed the chrome trim around the windows to paint it. For reasons I'm not going to get into here I had to remove my car from his shop before they could reinstall the trim. So anyway I was wondering if anyone could give me a little instruction on how to go about installing the trim. I already tried once with the rear window and it wouldn't seat properly, was poping up in places making me very frustrated so I pulled it back off and put it new clips. I also have some better trim I just bought so I want to do it right this time.