public void Post()
    {
      string args = GetPostUrlArgs();
      string result = string.Empty;
 
      HttpWebRequest objRequest = (HttpWebRequest)WebRequest.Create(@"https://secure.authorize.net/gateway/transact.dll");
      objRequest.Method = "POST";
      objRequest.ContentLength = args.Length;
      objRequest.ContentType = "application/x-www-form-urlencoded";
 
      StreamWriter myWriter = null;
      try
      {
        myWriter = new StreamWriter(objRequest.GetRequestStream());
        myWriter.Write(args);
      }
      finally
      {
        myWriter.Close();
        myWriter.Dispose();
      }
 
      HttpWebResponse objResponse = (HttpWebResponse)objRequest.GetResponse();
      using (StreamReader sr = new StreamReader(objResponse.GetResponseStream()))
      {
        result = sr.ReadToEnd();
        sr.Close();
        sr.Dispose();
      }
 
      this.Response = new CcTxResponse(result);
    }