rivergrl... wow, bike etiquette says that you ALWAYS ask someone who is stopped if they're OK. Sorry to hear people passed her without checking.

Here in San Diego, the local LBS's offer free beginner maintenance classes. You may want to check and see if any near you offer that. They teach you how to fix a dropped chain, how to change a flat, both front and rear, how to use a patch kit, how to use CO2, how to make minor derailleur adjustments to prevent chain hop (common as a new bike breaks in) etc...

good luck and you have earned some good bike Karma by stopping to help someone!