Add password protection for Admin section in VB.net

This site: [login to view URL] Has an admin section that I need to add password protection to. The site is written in VB.net. The admin section will need to have two levels. A user level where users can log in to edit the site through the existing admin pages. And an Admin level which allows administrators to log in and make changes using the existing admin pages as well as manage the users. Like this: User level - this level can log in and make changes to the site (the admin pages are already built, they just need to be password protected. They can also change their own password, but can not edit any other user information. Admin level - this level can add, delete and edit users. Admin level can do everything that regular users can do. There are about 75 pages that will need to be password protected. Outside of adding the password protection I also need pages built that will allow admin level users to add, delete, edit users. And a page that will allow existing user level to change their password.