Thats not how it works really no. I arent overly familiar with Drupal, but I would assume it has a 'URLstring' or simply a 'title' (or similar) field for news posts and page records etc. That field string will be pulled out of the DB and used in the URL.
Basically what mod_rewrite will do for you is use a rule which you specify in order to read the key bits of dynamic data in a URL.
I.e, if you have:
You can specify a rule in a .htaccess file to tell the server how that URL relates to the original, i.e:
It will know that whatever number which comes after 'article' in the rewritten URL is the id variable. In this case, the server wont care what comes after that and the 'how-to-grow-your-own-carrots.html' bit is irrelevant to it. That is just your SEF bit.
I'm no mod_rewrite guru so you're best off looking at the tutorials. It's pretty hard to get your head around at first!
If you post a link to a dynamic page on your site, I could look at an appropriate .htaccess file to put at your site root folder and see if we can get it up and running for you. Your host will need to allow .htaccess though, and this is assuming you are using PHP.