Custom user access level management for asp.net pages .

First off, i have 3 different user levels of admin, operator, and reports for my website.
 When user open the website they come to the login page (which i have done). On the basis of user levels, page will be accessed..
 
I tried creating common class and function inside it so that i will check user level on each page by just using that class's function or before loading each page , let page auto check for user level to access it. How to do this??? I and trying to generate code rather then using ASP.NET Configuration wizard.
 
 I am trying this since last three days. Please help me out. Thanks
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