Hi There,
Thanks for writing in! Because this requires a template change, I’d advise that you setup a child theme. This allows you to make code changes that won’t be overwritten when an X update is released. After your child theme is setup, please review how we recommend making template changes in Customization Best Practices.
Then add this bit of code on your child theme’s functions.php file
add_action('wp_head','my_tracking');
function my_tracking () { ?>
<script src="//www.xyz.net/am/00000/impressions/page/am.js"></script>
<?php }
Paste it just right after the
// Additional Functions
// =============================================================================
Hope it helps, Cheers!