integrating current website with php database

[ThePiston]

I currently run a website, but now I want to let about 70 people log into a "members" folder where they will have a forum and can change their passwords and personal information. I've already got the website and a mysql server. I'm on a shared server so I don't think I can install anything on it. Can anyone tell me how to go about doing this? My friend is already helping me set up the database, but I don't know how to implement it. THanks