Hi ,
It explains about the difference between Git & GitHub along with usage of both.
References:
https://trailhead.salesforce.com/en/content/learn/modules/git-and-git-hub-basics
https://guides.github.com/introduction/flow/
https://trailhead.salesforce.com/content/learn/projects/develop-app-with-salesforce-cli-and-source-control
https://git-scm.com/download/win
https://guides.github.com/activities/hello-world/
https://confluence.atlassian.com/bitbucketserver/basic-git-commands-776639767.html
https://www.youtube.com/watch?v=FyfwLX4HAxM