You only have to set this up once per machine.
git config --global user.name 'Jennifer Bryan'
git config --global user.email 'jenny@stat.ubc.ca'
git config --global --list
In words …
From RStudio, go to Tools > Shell and tell git your name and GitHub email by typing (use your own name and email):
git config --global user.name 'Jennifer Bryan'
git config --global user.email 'jenny@stat.ubc.ca'
These commands return nothing. You can check that git understood what you typed by looking at the output of git config --global --list.
Resources:
Go back to the index for the all the Git stuff.