You will need to be able to edit the file
.htaccess
(note opening dot)
To get the server to parse your .html and .htm pages for php code, you need to create or modify your .htaccess file in your public_html folder, to have the following lines:
AddType application/x-httpd-php .html
AddType application/x-httpd-php .htm
see http://faq.hostrocket.com/data/fetch.php?page=52
BTW: messing with .htaccess can have some SERIOUS CONSEQUENCES. Work carefully. Avoid typos.
Always keep a BACKUP before you mess around.
Signed
ONE WHO KNOWS (the hard way)