Make sure that your pages have ".php" extension and that your server is running php. Then, on each page type the following php code:
<?php include("analyticstracking.php"); ?>
Or if your analytics file is placed in different directory than your pages:
<?php include("some_directory/analyticstracking.php"); ?>
As opening tag they mean the <html>
tag at the top of the code.
Here is an example:
HTML/PHP PAGE CODE:
<html>
<?php include("some_directory/analyticstracking.php"); ?>
<head>
<!-- your head content goes here -->
</head>
<body>
<!-- your body content goes here -->
</body>
</html>
Hope that helps you...