By far, the best tutorial is the one on the Python website.

http://docs.python.org/tutorial/index.html

Chapter 9 is about classes.

http://docs.python.org/tutorial/index.html

Print it out and read it over coffee.

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)