First, make an .htaccess file that has this in it:
<FilesMatch "news$">
ForceType application/x-httpd-php
</FilesMatch>
Now, whenever you visit http://www.example.com/news/ It'll fun that script. Next you need to write a small script to read in and parse out the query string, so that you can get the news ID.
You can do this by explode()ing $SERVER['PHP_SELF'] I belive, if that doesn't show it, use $SERVER['REQUEST_STRING'] or some such, its one of the PHP predefined variables.
Hope that helps!