Adding an existing project to GitHub using the command line
Putting your existing work on GitHub can let you share and collaborate in lots of great ways. If you are migrating your project from CodePlex, read the migration guide for more information. Warning: Never git add, commit, or push sensitive information to a remote repository.
https://help.github.com/en/github/importing-your-projects-to-github/adding-an-existing-project-to-github-using-the-command-line