# advertise that we want to store a file.
    # $filename should probably not contain a path
    my $conn = $ftp->stor( $filename ); 

    # open the local file
    if( open my $fh, $filename ) {
      my $buf;

      while(my $read_bytes = read($fh, $buf, 1024) > 0) {
        $conn->write($buf, $read_bytes);

        # add your progressbar update here
      }
    }