by Stephen Fedder.
Have you tried the Moodle docs?
http://docs.moodle.org/26/en/Main_page
That is probably the best way other than using it in the trenches!
There are a number of books out there other than Moodle for Dummies
OReilly has their Using Moodle book and Packt Publishing has a number of Moodle titles as well. Just search their websites. If you are looking for something more specific, you have to be more specific with your question.