phpStats help

Hello, I downloaded phpstats, and installed it with no problems, however, they provide a string of code that you are supposed to put on every page that you want monitored
eg: <?php
define('__PHP_STATS_PATH__','/env/data/www/sitename/htdocs/stats/');
include(__PHP_STATS_PATH__.'php-stats.redir.php');
?>

I put it in index.php inside my current templates dir and seem to track just fine, but it only monitors the main page, not the posts pages, and I belive this is because the string is supposed to be in that pages code.

So the thing is: how do I add this code to the previous posts pages and how do I make sure it is implemented in new posts?

Thank you