What's the best way to master ZODB?

i am a beginner to the Plone CMS and i cannot find a proper place to learn and master the ZODB of Plone CMS , how should i begin ...?

You could start with the documentation:

https://zodb-docs.readthedocs.io/en/latest/

and the tutorial:

https://zodb-docs.readthedocs.io/en/latest/tutorial.html