Group work from scratch is best done as follows.
pull
their changes first, and then retry the commit.
Todays part of my tutorial will focus on that.
My tutorial is on http://wetware.work, at this link: http://wetware.work/prez/introducinggit/. Skip to slide 16, we will work from there through slide 37. You will practice, and we shall push on with branching in the next, and last git lesson.