i am sure this is very common thing to do. how do i do it. currently i used the ASP.NET Configuration tool but even when not logged in i can access the folders. this is what my Admin/web.config looks like after editing it after searching for info on this, but its not working.

CODE
<?xml version="1.0" encoding="utf-8"?>
<configuration xmlns="http://schemas.microsoft.com/.NetConfiguration/v2.0">
  <location path="~/Admin">
      <system.web>
        <authorization>
          <allow roles="admin" />
          <deny users="*" />
        </authorization>
      <authentication mode="Forms">
        <forms loginUrl="~/Home/Login.aspx"
          defaultUrl="~/Default.aspx" />
      </authentication>
    </system.web>
  </location>
</configuration>