Change Asp,net Authorization Programmatically

when i want to change the authorization rules of an asp.net application either i have to change the web.config manually
or i have to use the admin tool which will do the same, what if i want for an admin user in my application to create his own
roles(already did) and assign these roles to a specific pages(rules),should i have to implement this(create my own authorization)
manually or not. 
 
Any ideas
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