Creating and Manage roles using LDAP access

I need assistance do the following:

Creating and Managing Roles
Assigning Roles to Users
Role-Based Authorization

using LDAP authentication under ASP.NET 3.5, C# 3.0.

I attempted to search under Google but had no success.

The Goal is to be able to give LDAP user access to certain pages within the site

 For example;

     Have designated LDAP users have access to admin full access of the site

     Have designated LDAP users have access to portions of the site (certain pages are allow for them to have access)

I'm looking for a tutorial or step to consider when implementing this so I can learn and master.