How to manage role/User rights with sitemap

Hi experts

i would like to know how to manage role/user right in asp.net because in my actual website i create some role and rights like this :
(a folder is a folder in the root of my website)

role 1
  access folder 1 : Yes
  access folder 2 : Yes
  access folder 3 : No
role 2
  access folder 1 : Yes
  access folder 2 : No
  access folder 3 : No
role 3
  access folder 1 : No
  access folder 2 : No
  access folder 3 : Yes


and in each webpage i'm doing this :

  If User.IsInRole("Admin") Then
                mMenu.DataSource = ClsMisc.GetSiteMapDataSource("~/Navigation/SuperAdmin.sitemap", "~/UniquePageSuperAdmin.aspx")
            ElseIf User.IsInRole("Modérateur") Then
                mMenu.DataSource = ClsMisc.GetSiteMapDataSource("~/Navigation/Admin.sitemap", "~/UniquePageAdmin.aspx")
            End If


i have to test each role to bind the correcte sitemap for the current user
so if i have 300 roles... i don't think it's a good solution for managing role and/or user rights

Please HELP ME!!!

kind regards.