Adding user to certain roles

I have setup ASP security in my application. I used the following tutorial, just wondering if someone can tell me how i can setup this up to allow the creation of a user?
http://weblogs.asp.net/scottgu/pages/Recipe_3A00_-Implementing-Role_2D00_Based-Security-with-ASP.NET-2.0-using-Windows-Authentication-and-SQL-Server.aspx
Can someone tell me where to find or what to search on to find some example of how to add the option for adding users?
I have the above setup and its working, but only because of the accounts i created with my global.asax file.
I need to give the admins access to add a new user. Currently i can search on existing users and update them, but need to add the ability to add a new user.
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