class { ...
        String ftpServerIP;
        String ftpUserID;
        String ftpPassword;
        String uri = "";
        ThreadSafe _thSet;
        ResourceManager rm;
        FtpWebRequest reqFTP;

//Konstruktor
public FTP(String server, string user, string pw, String dicPictures, ResourceManager rm) {
            Debug.WriteLine("***** [FTP] *****");
            ftpServerIP = server;
            ftpUserID = user;
            ftpPassword = pw;
            uri = "ftp://" + ftpServerIP + "/" + dicPictures + "/";
            this.rm = rm;
            reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri(uri));
            // Provide the WebPermission Credintials
            reqFTP.Credentials = new NetworkCredential(ftpUserID, ftpPassword);
            reqFTP.KeepAlive = true;
            reqFTP.Method = WebRequestMethods.Ftp.UploadFile;
            reqFTP.Timeout = System.Threading.Timeout.Infinite;
            reqFTP.Proxy = null;
            // Specify the data transfer type.
            reqFTP.UseBinary = true;
            reqFTP.UsePassive = true;
            reqFTP.Method = WebRequestMethods.Ftp.UploadFile;
        }

        // Uploadmethode
        public bool Upload(string filename, String folderName, ProgressBar prgBar, Label lblStat) {

            FileInfo fileInf = new FileInfo(filename);          
            Stream requStream = null;
            FtpWebResponse resp = null;
            // Create FtpWebRequest object from the Uri provided
            try {
                requStream = reqFTP.GetRequestStream();
            }
            catch (Exception ex) {
                Debug.WriteLine("[ERROR] Fehler beim Empfangen des RequestStreams \n" + ex.Message + "\n" + ex.StackTrace);
                return false;
                throw;
            }

            FileStream fs = null;

            try {
                byte[] buff = new byte[2048];
                int bytesRead = 0;
                int actSize = 0;
                long fileSize = fileInf.Length;
                fs = File.OpenRead(filename);
                while (true) {
                    bytesRead = fs.Read(buff, 0, buff.Length);
                    if (bytesRead == 0) {
                        break;
                    }
                    requStream.Write(buff, 0, bytesRead);
                }
                requStream.Close();
                resp = (FtpWebResponse)reqFTP.GetResponse();
                Debug.WriteLine("[INFO] FTP Upload erfolgreich");
                return true;
            }
            catch (Exception ex) {
                MessageBox.Show(rm.GetString("FTPErrorUpload") + ex.Message);
                Debug.WriteLine("[ERROR] FTP Upload fehlgeschlagen\n" + ex.Message + "\n" + ex.StackTrace);
                return false;
            }
            finally {
                Debug.WriteLine("[INFO] Beenden resp; requStream, fs");
                if (resp != null) resp.Close();
                if (requStream != null) requStream.Close();
                if (fs != null) fs.Close();
            }
        }

Aufruf im Programm:

FTP ftp = new FTP(userConfig.urlFTPServer, userConfig.usernameFTP, userConfig.passwordFTP, userConfig.dicPictures, rm);

foreach (string uploadImg in FileNames) {
   ftp.Upload(uploadImg, tbxNameAlbum.Text, prgUploadFile, lblTextStatFile);
}