Given that the XML isn't "well formed", I'm not sure why you would want to generate it, much less output it to a file. But in the interest of getting the job done with as little work as possible (in the true spirit of how you asked your question):

use strict;
use warnings;
use autodie;
my $xml = <<'HERE';
# copy and paste here all the XML you posted
# in the node above.
HERE
open my $fh, '>', 'new.xml';
print $fh $xml;
close $fh;
#done.
[download]

If you wish to show us what work you've done to get started on the project, what you're doing to prepare the data structure that you wish to dump to XML, and where you're stuck, I'm sure we'll be happy to put more work into helping you with a solution.