Online Video tutorial for basic stuff (between iPhone and MacOS)- please help!

Need online video help explaining real basics of how to use iPhone with Mac OS. After owning many iPhones and Macs over the years, my photos are all messed up (in my view).

I have back ups on Mac but cannot view any Pics on Mac.

Is there a simple step by step process that explains how to use iPhone and Mac without issues? There seems no issue on a Windows environment... I am planning to clean up years of Photos....

Please help!!