Here is the simplest way to add Google or any other analytics/tracking code to this template although there are plugins available on the JED that will aslo do the job if you do not like playing with the code.
Copy the file plugins>system>jat3>jat3>base-themes>default>page>default.php into templates>ja_your-template-name>page>default.php and insert your analytics code just before the </head> tag as per below.
<head>
<?php //gen head base on theme info
$this->showBlock ('head');
?>
<?php
$blocks = T3Common::node_children($this->getBlocksXML ('head'), 'block');
foreach ($blocks as $block) :
$this->showBlock ($block);
endforeach;
?>
<?php echo $this->showBlock ('css') ?>
************YOUR ANALYTICS CODE HERE*************
< /head>
Or there are numerous extensions available on the JED that will do it for you.