Active Directory/LDAP and PHP

I am having one helluva time trying to do something which is simple on its face, but behind the scenes...ever so complex.

Ive search far and wide for example implementations but none seem to give me all I need.

I am looking to create parts of a website where one has to login using their Windows Active Directory login/pw in order to see anything within this section of the website.

I know I need to "tag" pages with a php script which checks for authentication on every page I want "locked out. LDAP seems to be the process for PHP integration with AD.

But I am having problems just even creating the simple login form which a user will use to authenticate.

http://www.php.happycodings.com/Cookies/code2.html
Seems best, but documentation is nil.
Anyone got a working example of such a thing?