private void button1_Click(object sender, EventArgs e)
    {
        FTPClient.Server = @"ftp.host.com";
        FTPClient.Username = "user";
        FTPClient.Password = "pass";
        FTPClient.Connect();
        UploadWorker UW = FTPClient.UploadFile(@"D:Testsomefile.txt", "public_html");
        UploadWorker UW2 = FTPClient.UploadFile(@"D:Transfersomeexe.exe", "public_html");
        UW.Start();
        UW2.Start();
    }