Authentication & authorization

The best tutorials are here

http://www.c-sharpcorner.com/UploadFile/lmoningi/AuthenticationAndAuthorizatio11252005233533PM/AuthenticationAndAuthorizatio.aspx

http://www.dotnetfunda.com/articles/article979-aspnet-authentication-and-authorization.aspx 

http://www.asp.net/web-forms/tutorials/security

http://www.asp.net/web-forms/videos/authentication