Hi RDW –
Welcome!!
I learned WordPress simply by experimenting with it. I recommend getting a free WordPress.com website and just have fun with it. Maybe make a blog documenting your adventure in learning WordPress or anything else you might like to share with people.
I think that you’ll find the help within the site to be more than adequate to learn with until you have specific questions but I also really love Lynda.com for learning software (this is a paid tutorial site).
There are also numerous WordPress experts who write tutorials and information on their own blogs (some paid and some free). I really like Carrie Dils, Bill Erickson, and Sridhar Katakam although they all write primarily about using WordPress with Genesis which is a paid premium WordPress framework that I use a lot.
The Elegant Themes people put together this article about places to learn which I think has some pretty strong suggestions as well.
I think it really comes down to how you learn best. By the way, great question! I hope this information helps.
Stephanie