Вы можете использовать HttpWebRequest , если UploadFile (как говорит OneShot) не работает.
HttpWebRequest как более детальные опции для учетных данных и т. Д.
FileStream rdr = new FileStream(fileToUpload, FileMode.Open);
HttpWebRequest req = (HttpWebRequest)WebRequest.Create(uploadUrl);
req.Method = "PUT"; // you might use "POST"
req.ContentLength = rdr.Length;
req.AllowWriteStreamBuffering = true;
Stream reqStream = req.GetRequestStream();
byte[] inData = new byte[rdr.Length];
// Get data from upload file to inData
int bytesRead = rdr.Read(inData, 0, rdr.Length);
// put data into request stream
reqStream.Write(inData, 0, rdr.Length);
rdr.Close();
req.GetResponse();
// after uploading close stream
reqStream.Close();