Welcome to the wonderful world of slack key guitar. There is truly no more soulful music on the planet.
The best way to learn is from sitting down with someone who plays. There are very active slack key groups in both Southern & Northern California.
Ozzie's book is the best. Even better, find a way to get to Hawaii and study with him; he's a gifted teacher.
If you really want some great, in depth study, check out Peter Medeiros' epic "Hawaiian Slack Key: A Lifetime of Study."
http://www.slackkeybypetermed.com/Home.html
Blowing my own horn for a moment (and who isn't surprised at that?
) I've got a couple things you might be interested in. Besides the book I did with KB, I've got a CD and TAB book called "Old Time Hawaiian Slack Key Guitar" and a pile of individual TABs on my website.
I've also got something like 45 hours of video lesson up at JamPlay.com. If you go to my website and click on the link, you can preview the lessons for one week free. (Ignore the awful free lesson Jamplay posted on YouTube--I was nervous and just rambled on and on without ever playing anything... someone needs a hook!)
http://www.mark-o.com
However you decide to proceed, I wish you much happiness in your musical journey.