ASP.NET

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class Instruction : System.Web.UI.Page
{

    OnlineExamsDataContext _mycontext = new OnlineExamsDataContext();
    string username;

    protected void Page_Load(object sender, EventArgs e)
    {
        username = Request.QueryString["username"].ToString();
        lbluname.Text = "Welcome   :" + username;
        lbldate.Text = System.DateTime.Now.ToString();


    }
    protected void btnstart_Click(object sender, EventArgs e)
    {
        int emailid;
        emailid = _mycontext.ExamTableInsert (Convert.ToDateTime (System.DateTime.Now.ToShortDateString()), Convert.ToInt32 (Request.QueryString["UserID"].ToString()), Convert.ToDecimal("0.0"));
        Response.Redirect("QuestionPaper.aspx");

    }
    protected void lbtnresult_Click(object sender, EventArgs e)
    {
        Response.Redirect("Examresult.aspx");

    }
}

I ought to redirect my website from non-www to www on IIS 6. e.g if I enter domain.com in the url, it has to redirect to www.domain.com for SEO optimization.

I followed the video "http://www.youtube.com/watch?v=PYxabNrIMQ4" for creating my rewrite rule. And I made it as below

<system.webServer>
<rewrite>
<rules>
<rule name="Redirect to www" patternSyntax="Wildcard" stopProcessing="true">
<match url="*" />
<conditions>
<add input="{HTTP_HOST}" pattern="mydomain.com" />
</conditions>
<action type="Redirect" url="http://www.mydomain.com/{R:0}" />
</rule>
</rules>
</rewrite>

But it is not working as expected. Help me out to find the solution.

Note: My Visual studio shows warning like "The element 'system.webServer' has invalid child element 'rewrite'".

I believe it doesn't make any problem.