Using Git

Firstly, this linked guide is a good overview of what git is, but it may be a bit to absorb all at once: https://rogerdudler.github.io/git-guide/

Essentially - commit when you want to save your work. This could be when you complete a full set of work and the code passes all tests. It could be earlier as well, depending on how many other people are working on the project at the same time.

More Advanced

The above is useful for tracking and saving work as you go (especially important when working on BIG project)

The next information is for working with big groups of people, and tracking your work with better detail.