How to get an ipad, macbook and iphone to sync across all. I don't see any clear instructions.

I need the same to be on all but each one has it's own back up but not synced.

Anyway to talk to a human rather than back and forth and back and forth with emails?

I have had app for years but never been able to have one library, very frustrating.
I'm sure there is a way but don't see where.

Please and thanks,
Ed