How to work with git in Mern-Stack?

This morning I started with git. The latest tutorial came directly from Visual Studio Code and I was told to create a folder with some code and then go to source control and press the “Initialize Repository” button. So I created a react app, but in source control is only a button “Publish Branch”. Has anything changed there? If so, I am grateful for an up-to-date answer. On google I find no hints.