one Good one is the D3200 for Dummies. There is another book one by David Bush I got both from amazon I would have bought the one from the fellow on Nikonian that created the book for the D3000 but he evidently hasn't offered one for the 3200. The Dummies Book seems better written. It more understandable, and explains thing better.
Don't feel bad I have more trouble with focus on the 3200 than on my 3000. One thing the focusing pattern you see in the ViewFinder never gets in focus despite my adjusting the eyepiece. I've got a dopter corrector coming from Nikon. I think the issue is that the Sensor is so much better it tends make everything smooth even if in perfect focus On some things I can in Aperture adjust focus and looks better. Then some doesn't make that much difference.