There's an easy way to find out if your business is using a BES.
On your BlackBerry, check your Options->Service Books.
Do you have several Desktop entries that say the following:
If so, your company has BES. You're in luck! It may need to be configured (ie MDS turned on), you need to contact your system administrator.
However, if there is no Desktop entries, and if you're already paying for the BlackBerry yourself, you need to go to the Hosted BES FAQ: http://www.blackberryforums.com/viewtopic.php?t=53
You have to purchase this from a third party for about $10-$25 per month. You probably won't be involving your business in this; this would be completely a third party thing.