怎么通过HttpWebRequest 把数据发送到服务器上

如何通过HttpWebRequest 把数据发送到服务器上。
string url="http://*.*.*.*:8081/md/jsp/downloadData.jsp?sDate=2007-09-10";
HttpWebRequest hreq = (HttpWebRequest)WebRequest.Create(url);

  HttpWebResponse response=(HttpWebResponse) hreq.GetResponse();

  if (response.StatusCode == HttpStatusCode.OK)
  {
  Stream receive = response.GetResponseStream();
  Encoding encode = System.Text.Encoding.GetEncoding("utf-8");
  StreamReader resr = new StreamReader(receive, encode);
  Char[] read = new Char[30];
  int count = resr.Read(read, 0, 30);
  while (count > 0)
  {
  String str = new String(read, 0, count);
  // lstResults.Items.Add(str);
  returnString += str;
  count = resr.Read(read, 0, 30);
  }

  }
  else 
  {
  returnString += "not Connection";
  }
  response.Close();
以上代码功能能得到服务器上的数据，但是我想把ppc上的数据发送到服务器上，该如何实现

------解决方案--------------------
http://www.netomatix.com/HttpPostData.aspx
------解决方案--------------------
异步方式如下：
request.BeginGetRequestStream(new AsyncCallback(ReadCallback), requestState);
....

private void ReadCallback(IAsyncResult asynchronousResult)
{
RequestState requestState = (RequestState)asynchronousResult.AsyncState;

HttpWebRequest request = (HttpWebRequest)requestState.request;

Stream postStream = request.EndGetRequestStream(asynchronousResult);

postStream.Write(requestState.postData, 0, requestState.postData.Length);

postStream.Close();
}