Some quick tips from my own git courses:
When teaching, try not to lecture too much, instead, provide exercises and walk around to answer questions.
Don’t forget to instill, from the beginning, good git commit message habits. See the 7 rules here (scroll down a bit): https://chris.beams.io/posts/git-commit/
Maybe copy paste those and reference the source in the tutorial that you make.
Last, keep in mind that a lot of what people need to know about GitHub is on the web interface - no need to introduce fancy command line too soon.