I'm very fluent in SL. I learned when I was very small and had quite a few deaf friends growing up. I think it is absolutely beautiful btw and love to sign songs. I used to sign songs in church while the chior sang.
I surprise people quite often with it. I had a deaf lady come into eat at the restaurant and she was sat at one of my tables. I noticed right away that she was deaf and started to introduce myself via sign language. She was one of the nicest ladies I've ever met and I had a total blast talking with her.
There are quite a few places you can learn sign language. My bestfriend growing up went to a private Christian school, and they had sign language classes there.
Kelley gave you lots of good tips. Also, if you have a hard time finding any information about Amercian sign language from any collges then you can "look it up" with Voc. Reh. Sometimes VR will refers you to a right direction to the ASL classes. I know one of my hearing friend who had a hard time finding any informations. She decided to contact with VR and VR referred her to the right spot. She took ASL classes etc.. I thought it is another way for you to find it.
The key is that if you hang out with a deaf person then you ll pick up and learn fast how to sign without going to the ASL class. It depends on indiviuals.