phpBB - Adding custom headers to very top of page

[KICKERMAN360]

Hi

I want to place my custom global header i made (called global_header.php) above my phpBB forums. I was going to at first just use the template files, since that's how a heavily customized the theme before, however, the theme files are .html. Is there a php file where I can add my include for the global header?

 

P.S. I'm kinda a php novice. Still learning the trade.

Thanks