I've taken two formal classes on bicycle maintenance, and several "informal" classes where fellow cyclists have offered to teach me how to do various things.
For the formal classes, check with:
-- your local university or college - they often put on a basic bicycle maintenance class on a day or two during the spring or summer. (that's where I took my first class)
-- your local community classes - you know the "leisure guides" most towns put out offering classes in pottery, yoga, beginner's French, etc. ... well sometimes they have a bicycle maintenance class too.
-- your LBS - sometimes they put on a class. In fact, in the previous place I lived, one LBS put on a course that was held once a week throughout the winter (10 or 12 weeks, I think) and got quite in-depth. I would have loved to take that one, but it didn't fit into my schedule then.
-- places like MEC and REI - they often have a whole series of classes on various sports and bicycle maintenance is one of them. (that's where I took my second class)
-- your local bicycle touring club - I've often seen those clubs offer a bicycle maintenance class, especially shortly before any of their bigger tours.