求指点下淘宝登录 webbowser控件

[Arz_math]

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace Taobao
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            Taowb.Url=new Uri("http://login.taobao.com/member/login.jhtml?redirect_url=http%3A%2F%2Ftaojinbi.taobao.com%2Fhome%2Faward_exchange_home.htm");
            Taowb.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(Taowb_login);
        }

        private void Taowb_login(object sender, EventArgs e)

        {
            HtmlElement username = Taowb.Document.GetElementById("TPL_username_1");
            HtmlElement password = Taowb.Document.GetElementById("TPL_password_1");
            username.InnerText = "丝222";
            password.InnerText = "1111111";
            HtmlElement submit = Taowb.Document.GetElementById("submit");
            submit.InvokeMember("click");
            MessageBox.Show("new game");
        }

    }
}