Further reading
Using dbt, you will not need to become a Git pro, but if you want to know more about the de facto standard, you can read the Pro Git book, written by Scott Chacon and Ben Straub and published by Apress, which is available online for free at https://git-scm.com/book/en/v2.
If you want to explore all the available features of GitHub, you can explore the GitHub docs at https://docs.github.com/en.
There are plenty of books and web resources about Agile, but I liked the practical style of Henrik Kniberg in his “from the trenches” books about Scrum, XP, and Lean development.