I spent several hours trying to understand Google's

I spent several hours tries to understand Google's instructions and got very confused with implementing analytics.

We have been using Google analytics for a long time and we have a WP plugin installed where we include our tracking ID# and that's all, everything's peachy.

Last week we upgraded to Google Universal Analytics that requires us to embed this code into either a php or .js file.

<script>
(function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
(i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
})(window,document,'script','//www.google-analytics.com/analytics.js','ga');

ga('create', '#####', 'erickson.edu');
ga('send', 'pageview');

</script>

1. Google says this is optional:

PHP Implementation - optional

Create a PHP file named "analyticstracking.php" with the code above and include it on each PHP template page. Then, add the following line to each template page immediately after the opening <body> tag:
<?php include_once("analyticstracking.php") ?>

2. If you haven't implemented the analytics.js tracking code, you are still using ga.js to send data to Google Analytics. If you continue to use the ga.js version of the tracking code exclusively, your data will be handled by Universal Analytics processing, but you will not get all the benefits of Universal Analytics.

To find out which version of the tracking code you're using, look for either analytics.js or ga.js in the code snippet on your web pages. If you see the text ga.js, you're using the old version.
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I checked we don't have any .js file, tracking is done via WP plugin...
So where do i embed that code for everything to work good?
Please help!