Sorry to hear about your bike getting stolen. I live in SF, too, and even though I keep my bikes locked in a garage, I'm still paranoid about someone breaking in and stealing them. A couple of great resources here, in SF, for learning about building/working on your own bike are: The Bike Kitchen and SF Yellow Bike. They both have mechanics there to help, along with the necessary tools, and typically will let you volunteer if you can't afford to pay the small shop fee.