This article is not about what git is. You can learn about git in this article. That article should suffice to get you started on git. It’s very important that you know what git is and why it is so crucial. It is one of the core tools in the toolkit of a professional app developer. This article shows how to access a remote repository using SSH. If you just want the solution, you can skip everything and go to summary, though I recommend reading the article line by line.
Two Ways to Access a Remote Repository