Hi Grace,
The book Using Moodle is free to download in PDF format. It concerns version 1.8 but most things haven't changed.
For Moodle 2 there is Mary Cooch's Moodle 2 First Look - in fact I'd recommend any of Mary's books and UsingMoodle video tutorials.
For specific questions, I usually do a Google search which gets me to a relevant forum discussion or the Moodle docs.
Cheers,
Glenys