Git In Two Minutes (for a solo developer)
https://www.garyrobinson.net/2014/10/git-in-two-minutes-for-a-solo-developer.html

tldr;
git init
git add .
git commit -a -m "This is your commit message for all changed files"
git log --pretty=oneline
git log
git checkout HEAD -- <filename>
git checkout 179e59467039 -- myfile
git diff HEAD -- <filename>
git diff <hash1> <hash2> -- <filename>
git reset HEAD^
git commit --amend -m "Replacement commit message"
git status