Well, it's simple enough. You have a database containing all the changeable information, and when you change the information you have PHP write out a new version of the entire HTML page (overwriting the previous version).
You could use some template facility to expedite the process (there are plenty of articles (such as "Template framework for static sites") and bits of code elsewhere on this site), or you could just do what amounts to:
fwrite($htmlfile, "< html >
<head><title>News</title>
<body>
<table width="95%" border="2">
<? get news items from database, print them out
?>
</table></body>");