Here is how you can insert your Google Analytics code into JA T3 . . .
* Go to folder /public_html/plugins/system/jat3/jat3/base-themes/default/page and edit default.php file.
* You should find the tag </head> or <body>
* You need to paste your Google Analytics tracking code just before this </head> tag or after <body> tag
Now you can close all your files and relax as Google Analytics collects information for you.
Another way would be to go to the Joomla Extensions directory and there you will find a number of great extensions that will do it all for you.
Hope this helps!
😎