Help with users management.

Hi,

I'm developing a web application for a intranet enviroment, and i need some help with the users management.

this is what i need to do:

1. The first time that the user enter to the site, i want to authenticate them with the active directory for use all the
   information inside the AD (username, password, email, etc)
2. All this information i want to store it in my own database (aspnetdb that is use it with asp.net membership)
3. with the user authenticated with Active Directory and all the information of the user in the aspnetdb, i want to use role management (with asp.net membership) for all users of my web application

Anybody that can help me with this, the part that i do not know how to do it, is authenticate the user with Active Directory and store this information in my own db tables.

thanks a lot.
...