includes in page extension .html

Its not ideal but you can setup a server to parse PHP in HTML pages via .htaccess - it makes the server work harder, and web pages slower, but it can be done (if the server is set up that way). Here's some info in that: http://stackoverflow.com/questions/4...n-as-php-files

If it doesn't work, speak to your web host as you might not have the appropriate privileges or the server may not be setup that way. If it isn't, you won't be able to use PHP in .html pages so you'll need to change the extension to .php