Are you asking how do you protect certain pages from being viewed if a visitor is not logged in? That is handled using sessions. You'll need to pick a server-side language (such as PHP, ASP, Ruby, etc) and handle the pages on that side of things.
The basic idea is when you verify a user's account name and password, you set a session variable up that persists across all pages, and then at the top of any page you want to protect, check that session variable and if it's set correctly, display the page.
If your question is not the one I answered, sorry about that-- ask it again another way.