The first Git lesson taught during CodeRefinery workshops assumes some previous experience with Git. This short lesson goes through the necessary installation and configuration steps, and also covers some of the very basics of Git which are helpful to know before the workshop starts.
The following Gemfile will permit you to run jekyll locally
source 'https://rubygems.org'
gem 'github-pages', group: :jekyll_plugins
gem 'github-linguist'
gem 'rouge', '~>1.11.1'
Write it as Gemfile under the repository root.
$ export GEM_HOME=$HOME/.gem
$ export PATH=$PATH:$HOME/.gem/bin
$ bundler install
$ bundle exec jekyll serve