You can create page in Frontpage and then have it post to a php page which in turn can store data in a database. You would have something like
<form action="update_database.php"
The update_database.php wouldn't care if the original page was made by Frontpage. $GET and $POST will work just fine.
But, you probably also want to take data out of the database and add it to the pages generated by Frontpage. In which case, assuming you are determined (or required) to use Frontpage, you need to learn about templates.
There are several articles on this site. Basically, with templates you add special tags to your Frontpage generated html. The php template processor reads in the html and replaces the tags with data.