Photos Application On A Mac: Class Tutorials and Handout
Below are links to tutorials for Photos and also two YouTube Video tutorials (scroll down.)
Green Valley Camera Club Classes: Feb. 7 and 14, 2020
Photos Users' Guide: MacOS Catalina - by Apple
How to use Photos for OS X: The ultimate guide: iMore
Good written information, just ignore the ads.
New Live Photos Features: Edit them in OS High Sierra
New Features in the Photos App in macOS Catalina
Beginning Tutorial on Photos in Mac OS High Sierra. There are some changes with this version. 56 minutes.
The YouTube video below is about 23 minutes. This is the older version, for Yosemite.