Where do you live? Find a local club website and they usually have links to race sites in the area. Here in Indiana they have this thing called the Indiana Race Series or IRS, and they have a website with a schedule on it. Maybe there is something similar in your area.
You don't have to join a team if you don't want. There are lots of pros and cons, but remember that you're allowed to ride on your own if you want. It's a good idea to go to
www.usacycling.org and get a license. They cost $60, but if you don't have one you'll have to get a one-day license and eventually you'll end up spending $60 anyway.
Just train and go do one. I just had my first race, and nothing can teach you better than just getting out there and doing it.