SSL/Https Global.asax

this is so that people would like me how to https with www and without www on such that all my sends me over to the side with https www and without www.

I've tried to do like this:

if (!Request.Url.Host.StartsWith("www") && !Request.Url.IsLoopback)
    {
        UriBuilder builder = new UriBuilder(Request.Url);
        builder.Host = "www." + Request.Url.Host;
        Response.Redirect(builder.ToString(), true);
    }