How are you doing this all? Is this using github's web interface? Github is not git. Github is a website that hosts git projects (aka repos) on a server.
Git is a program which is used to control changes to files, and allow you to see history.
Whilst you can use Github online to make changes, it's not the "right" wayThe two main ways of using git is
1. With a command line. That's what the git add etc is referring to, it's what you type into a command line. If on Windows, get "Git Shell". If on Debian/Ubuntu, type sudo apt-get install git-core. You'll need to set up your email and name. Use the same email as you do for Github. Note that the email you use is visible by anyone that can see the commit logs (for example, it would be publicly visible if you host the repo on github publicly)
2. With a desktop program, for example "Github for Windows". This allows you to graphically add files and make changes.
Folders don't exist in git, only files: therefore you can't add an empty folder, it must have files in it.
Git is hard to learn, but once you're good with it it makes things a lot easier. (in terms of backing up code, managing Dev and stable versions, working with others).
Relevant:
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