upload

using (SftpClient client = new SftpClient(serwer, port, user, pass))
            {
                client.Connect();
                client.ChangeDirectory("/var/www/html/img");
                using (FileStream fs = new FileStream(Path.GetFileName(Upload.FileName), FileMode.Create))
                {
                    client.BufferSize = 4 * 1024;
                    client.UploadFile(fs, Path.GetFileName(Upload.FileName));
                }
            }