Member login requires a database. You have to keep track of, at minimum, their user name and password. So hopefully you have a basic knowledge of databases. Note that users loose or forget their passwords and user names regularly so you will need to allow them a way to reset them as well. Which usually means you keep their email in the database and if they loose their password you send an email with the user name and a new password.
You then use a session to keep track of them as they move from page to page. So you will want to also read up on the [man]session_start]/man] function. And if you haven't worked with sessions before I would recommend reading some tutorials.
