In my application I have different roles and offcourse multiple pages. How do I secure webpages that may not be accessed by certain roles?
Imagine group 1 has acces
This is a big topic but I think what you want to look into is the ASP.NET Membership Provider.
I would start here: Examining ASP.NET 2.0's Membership, Roles, and Profile.
There's one thing messageboard websites, eCommerce websites, social network websites, and portal websites share in common: they all provide user accounts. These websites, and many others, allow (or require) visitors to create an account in order to utilize certain functionality. For example, a messageboard website, like ASPMessageboard.com, allows anonymous and authenticated visitors to view and search the posts in the various forums. However, in order to be able to post a new thread or reply to a message a visitor must have an account and must log into the site.