parse is used to store XML in a variable named $twig.

#!/usr/bin/perl
use strict;
use warnings;
use XML::Twig;

my $twig = new XML::Twig;
$twig->parse('<?xml version="1.0" encoding="UTF-8" standalone="no"?><food><name>Apple</name></food>');
$twig->print;

The following should be returned.

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<food><name>Apple</name></food>

Notice that the XML is inline instead of indented. pretty_print can be used to indent the output.

my $twig = new XML::Twig( pretty_print => 'indented' );

Now the output should be indented.

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<food>
  <name>Apple</name>
</food>

parsefile is used to parse XML in a file.

my $twig = new XML::Twig;
$twig->parsefile('foo.xml');
$twig->print;

children can be used to only print the <name> tags.

foreach my $name ($twig->root->children('name')) {
  $name->print;
}

Which should return the following.

  <name>Bugs Bunny</name>