Try this

#!/usr/bin/perl
use strict;
use warnings;

open FILE,"<file.txt";
my @array = <FILE>;
close FILE;

foreach(@array){
    if(/^.+?:\s(.+)$/) {
        open NEW_FILE, ">>new_file.txt";
        print NEW_FILE "$1\n";
        close NEW_FILE;
    }
}
[download]

The regex match should match anything after the colon and by using $1 uses that match. Use your own file names also.