帮忙完整的解释下代码 c#

Question

  protected void Button2_Click(object sender, EventArgs e)
    {
        CookieContainer cc = new CookieContainer();
        string SEntry = "http://passport.baidu.com/?login";
        HttpWebRequest request = (HttpWebRequest)WebRequest.Create(SEntry);
        request.Method = "POST";
        request.ContentType = "application/x-www-form-urlencoded";
        request.AllowAutoRedirect = false;
        request.CookieContainer = cc;        byte[] PostData = Encoding.Default.GetBytes("username=" + TextBox1.Text + "&password=" + TextBox2.Text + "&mem_pass=");        request.ContentLength = PostData.Length;        using (Stream sm = request.GetRequestStream())
        {
            sm.Write(PostData, 0, PostData.Length);
        }
        string strResult;
        HttpWebResponse response = (HttpWebResponse)request.GetResponse();
        response.Cookies = cc.GetCookies(request.RequestUri);
        using (Stream sm = response.GetResponseStream())
        {
            using (StreamReader sr = new StreamReader(sm, System.Text.Encoding.Default))
            {
                strResult = sr.ReadToEnd();
            }
        }
        response.Close();        request = (HttpWebRequest)WebRequest.Create("http://zhidao.baidu.com/q?ct=17&rn=25&lm=393738&tn=ikpsask2");
        request.CookieContainer = cc;
        response = (HttpWebResponse)request.GetResponse();
        using (Stream sm = response.GetResponseStream())
        {
            using (StreamReader sr = new StreamReader(sm, System.Text.Encoding.Default))
            {
                strResult = sr.ReadToEnd();
            }
        }
        response.Close();
    }