session as an application

I'm very new to ASP.NET, and am trying to get a handle on how to properly code this project I have.
I'm used to writing C#.NET applications with windows forms, so that is my background I am coming from.
What I want to do is write a ASP.NET site that a user on my domain can visit to add or remove other users from active directory security groups.
It's laid out real simple:
1) User navigates to this internal page; the website will store who the user is that visited the site
2) Website will list what security groups this user has permission to modify.
3) User can select which security group to modify and add/remove users as he/she pleases.


My general idea on how to do this (remember I am new to ASP.NET, so this will be off and my terminology may be incorrect, so where you can please correct my thought process):
Have an all encompassing class in a code file under App_Code. It could look somet ...