Maintain users list of Active Directory for an asp.net web application only

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C#3.0

C#

Hi,
I have configured active directory in my server 2008. We have a web project using asp.net mvc named Audit planning and Execution Software(Apex2).
What we want to do is to authenticate Active directory users for this project.
I can get all active directory users, groups, users of a group etc.
I want to add users in active directory for the Apex2 project only using asp.net.
I also want to display only the users and groups of Active Directory registered with the Apex2 project only. And I also want to add active directory users from whole AD list to our project's AD list.
Can you please tell me, how will I do this. Shall I create an Organizational Unit and maintain all users and groups there for our project? or is there any other way to do this?

Thank You