How can i use this code in mvc web application

i want use this code for [Authorize] users. but i dont know how it work. i use ado.net for login user and save username in webbrowser cookie.

public class CustomAttribute:AuthorizeAttribute
{
    public override void OnAuthorization(AuthorizationContext filterContext)
    {
        base.OnAuthorization(filterContext);
        IsUserAuthorized(filterContext);
    } 

    private void IsUserAuthorized(AuthorizationContext filterContext)
    {
        if (!filterContext.HttpContext.Request.IsAuthenticated)
         {
          //my code
         }
        if (filterContext.Result == null) return;
         }

         }