Well, you can embed php code into HTML code,
example:
<head>
<title>something</title>
</head>
<body>
<?php
// Comment: including the stuff file
include 'dir/file.ext';
?>
</body>
It's kind of easy, just remember to include the right file, make sure the extension is correct and everything you try to include 🙂
Hope it helped, Arni