upload file in c# with HttpWebRequest

string[] open = this.openFileDialog1.FileName.Split('\\');
           string nome = open[open.Length - 1];
           string[] temp = nome.Split('.');
           string extension = temp[1];
           HttpWebRequest req = (HttpWebRequest)WebRequest.Create(this.indirizzo + "servletUpload/controllerFiles");
           string post_data = this.openFileDialog1.FileName;
           string boundary = "AaB03x";
           string useragent = "_Webclient_Meetecho 1.0";
           req.UserAgent = useragent;

           req.ContentType = "multipart/form-data; boundary=" + boundary;
           req.Method = "POST";
           byte[] contents = FileToByteArray(post_data);
           MemoryStream postData = new MemoryStream();
           string newLine = "\r\n";
           StreamWriter sw = new StreamWriter(postData);
           sw.Write("--" + boundary + newLine);
           sw.Write("Content-Disposition: form-data; name=\"myFile\"" +"; filename=" + "\"" +  this.stanza + "-" + this.room + "."+extension + "\"" + newLine,"upload",this.openFileDialog1.FileName, newLine);
           sw.Write("Content-Type: application/octet-stream; charset=ISO-8859-1" + newLine);
           sw.Write("Content-Transfer-Encoding: binary" + newLine + newLine);
           sw.Write("VALUE" + newLine);
           sw.Write("--{0}--{1}", boundary, newLine);

           sw.Flush();


           postData.Write(contents, 0, contents.Length);
           sw.Write(newLine);


           sw.Flush();

           req.ContentLength = postData.Length;
           using (Stream s = req.GetRequestStream())

               postData.WriteTo(s);

          postData.Close();