It's common that if you use things like Codeception or Selenium for testing the current system only works with old browser versions. The issue when you don't use things like docker or vagrant for testing is that you may be using Firefox as web browser and having an old version will cause you problems.
When trying to explain how git works for people that wants to use it I found that the harder part is to get the global picture and to setup the base system. You cannot work with git without understanding how it works. This blog post tries to explain basics about how to use github.
You are here probably because you have read about the new joomla structure proposal. It's still not supposed to be available to the community but in fact it is. People starts having questions, starts asking themselves what is this about. This is MY opinion about it.