[NTLDR]

If you follow the example in there:

PHP Code:

// Example of how to include a seperate file: 
ob_start();  
require("yourheader.html"); 
$headercontent = ob_get_contents();  
ob_end_clean(); 


You could then put $headercontent (which should work in most cases, some templates will require $GLOBALS[headercontent]) will place the HTML found in yourheader.html where you have placed the variable.