You can access the User Guide any time under ‘Help’ in the NVDA menu. Press INSERT and the ‘N’ key or right click on the NVDA icon in your task bar.
There are a number of community-run email lists where NVDA users can answer each other’s questions. There are lists for various locations and languages available.
Training and Support
Various organisations around the world provide NVDA training. Some provide this service free. Some charge for the tuition, though the cost may be covered by a state agency in your region.