sudo apt install ruby-dev ruby-rubygems
gem install jekyll bundler
jekyll new myblog
cd myblog
Following the instructions from here isn't necessary, but recommended for testing locally. I haven't done it here.
cd /path/to/here
bundle exec jekyll serve --livereload
check the theme name in _config.yml: minima
bundle info --path minima
Copy the things you want to modify, from that path to this path.