5
You still need to install XOOPS and the includes will load your page with the theme you use for xoops. You would have to create a custom theme that goes with your other site.
Here are the includes you need to add to your html pages of your site, plus you have to save those pages as php.
include('mainfile.php');
include('header.php');
$xoopsOption['show_rblock'] = 1;
?>
Put the above at the top of your page before the first
include('footer.php');
?>
Put the above at the very end of your page after
Then save the page as php