child themes - add to info please

For those of us who have not used child themes before - I can tell you I have spent over one hour searching for how to make it function...

Please please add to the only manual info I could find the HOW.. part..
https://premium.wpmudev.org/manuals/the-buddypress-manual-2/what-are-parent-and-child-themes/

ie: you SIMPLY (if you know) move/copy (Still not sure which I was supposed to do so I copied) the CHILD folder to the main folder of the theme and activate the Child theme..

Thereby saving numerous grey hairs and much frustration....