where can i take some sports classes?

I want to learn a new sport, its one of my goals for this year. Tennis, badminton, or whatever, any outdoor competitive sport.

I go to the gym 6 times a week, plus yoga and swimming so im in good shape. I see various groups that meet up and play using meetup.com, facebook, forums etc. But im such a total beginner at pretty much all sports, I need to get some classes before I can play for fun. (I was a nerd at high school and never bothered with them).

anyone know some places?