Here are a few (other) good sites to learn about fixing bikes--

(until I take over the world)

first, Sheldon Brown. The man seems to have been a walking bicyclopedia. All sorts of information about...well, all sorts of things.

Park Tool. They make nice tools, and are a great resource for repair instructions. As is this one. This fella's made a bunch of videos about fixing bikes. Kind of nerdy (me too!), and really good.

If you are interested.