Analytics Install

Trying to install Google Analytics and it gives me a few ways to do it. I am thinking that the PHP method is best. So I save the tracking code as analyticstracking.php and upload into which folder on my site? Do I put it in the wp-content folder?

Also it says to include this line of code to the template page:

<?php include_once(“analyticstracking.php”) ?>

before the </body> tag. I have two template pages, a main index template and a page template. Here is the page template code:

[Code moderated as per the Forum Rules]

Where should I put the line of code in there and do I need to add it to the index template as well?