How does one find out about the Dom/sub community in their area?
Carefully. First, you have to find a BDSM community in your area. Obviously if you live near a larger city, you're going to have an easier time finding one. I would use the internet intially to find the names and contact information of groups.
Use your common sense - meeting people in a BDSM community is the same as meeting any other strangers. Make sure it's a public place, and that you feel comfortable. Check out anyone that you decide to play with - you can run background checks online. Your safety should take precedence over your other priorities for the meeting.
Also, be careful of people that only play online that suddenly want to meet in person. These people have a bare minimum of experience. You don't want them to practice on you.