Did I understand the process of installing google analytics on the site correctly?

Question

Google

I'm just about to launch my first website (like a business card), where I will learn and test different features. Now I want to try to install Google analytics to monitor visitors.
As far as I understand, I need

<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','https://www.google-analytics.com/analytics.js','ga');

  ga('create', 'UA-84967762-1', 'auto');
  ga('send', 'pageview');

</script>

paste this code into analyticstracking.php.
And add after the body tag to each file - <?php include_once("analyticstracking.php") ?>
but I have the body tag open. in the header, which is just a separate file, and others include it. That is, I only need to specify it there once and it will work all right?
And nothing else needs to be done ?, everything will work?

Answer 1

Insert in the header, which you have as a separate file.

Answer 2

Insert in header