you can try out the following free training course.

Learn NVDA:  http://www.afb.org/info/living-with-vision-loss/using-technology/assistive-technology-videos/learn-nvda/1234
There are also training courses here. http://www.nvaccess.org/shop/
And there is a book  Windows Screen Reader Keystroke Compendium: Covering JAWS, NVDA, and Narrator (SCREEN) http://www.nbp.org/ic/nbp/SCREEN.html
SwitchingFromJawsToNVDA https://github.com/nvaccess/nvda-community/wiki/SwitchingFromJawsToNVDA
NVDA Frequently Asked Questions(FAQ) https://github.com/nvaccess/nvda-community/wiki/FAQ
Hope this helps.