等待网页返回信息，然后再动作，思路不清晰了

用Stream resStream = response.GetResponseStream();返回网页信息，根据它的返回结果来动作
加线程休眠不起作用，我应该怎么做
for (int i = 0; i < 1; i++)
            {
                HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://x.cn/1.html");
                request.Timeout = 1000 * 5;
                //request.Method = "POST";
                HttpWebResponse response=null;
                request.ContentType = "application/x-www-form-urlencoded";
                try
                {
                    response = (HttpWebResponse)request.GetResponse();
                }
                catch(Exception ex)
                {
                    this.richTextBox1.Text = ex.Message;                }
                if (response.StatusCode == HttpStatusCode.OK)
                {
                    Stream resStream = response.GetResponseStream();
                    System.IO.StreamReader streamReader = new StreamReader(resStream, System.Text.Encoding.GetEncoding("gb2312"));
                    string BackText = streamReader.ReadToEnd();
                  
                    if (BackText == "ok") i = 0;
                    Thread.Sleep(3000);
                    this.richTextBox1.Text += BackText+"\r\n";
                    
                  
                }
              
            }