hello...
probably one of them has it - lemme look. what you need is some sort of database or flat file to store user's passwords - so they fill out a form and register, you save their info and then when they come back, they put in their login info and you match it against the saved profile...
something like this covers the basics:
http://www.swish-db.com/tutorials/view.php/tid/601
sitruc