You could try using one of the major press release distribution sites like prnewswire, prweb, etc to distribute them to the right media contacts.
Once you have an effective press release written, you can also try to find your own media contacts that are related to your niche or industry (or even locally).
Lou's right. Your press release can't just be an advertisement for your company. It has to be NEWSWORTHY. Meaning something unique, some major event/milestone/donation/etc .
There are a few sites with tips on writing a press release. Here's a good start:
http://www.prweb.com/pressreleasetips.php