New user to opencv need help in using it

Hello all my son said “don’t post your question to Facebook use Github you will get more and better help”

I have downloaded a opencv file as a zip from github and installed it to my Raspberry pi4b So the os is 64bit.
This is the file I’ve downloaded GitHub - Qengineering/RPi-image: Raspberry Pi 4 64-bit OS image with deep learning examples but being completely green/new to all things todo with Raspberry pi and opencv I don’t know where and how to start using the file I have installed and was just wondering if anyone can help me start using it. So what do I want from the program I have down loaded.

This is the easy part I hope I want a camera that will detect a face is in the shot and email a image to my email account.