Hey everyone, I am currently working on a website for someone and I designed it and did the front end code(do not know any php/mysql or any backend). Their current site has a store and such that they would like to keep and a login system where when they login they view the same site but the store has discounted prices. I am not sure how to do something like this and was wondering if I would get some advice. Maybe there is some pre made things online that I could hook up? Does not have to be anything real fancy.

Thanks in advanced!