Customize authentication

Hey there.
I have a Database which has some users and admins.
in my Table which stores users profile(tUser table) I have a field named"Security".
I have 3 kinds of users
1:Admins
2:Moderators
3:users.
also I have some pages which admins and moderators can visit those pages.
it means that if mySecurity field was 1 or 2 they can visit these pages.
so far so good.
this is my authentication in my webconfig
<?xml version="1.0"?>
<configuration>
    <system.web>
      <authorization >
        <allow users="vahid.ch"></allow>
        <deny users="*"/>
      </authorization>
    </system.web>
</configuration>
if u see I specify that only vahid.Ch can ...