# Gemfile To add new gems (libraries) you can edit the `Gemfile_custom` file. For example to add [rails-footnotes](https://github.com/josevalim/rails-footnotes) gem you would just add: ```ruby gem 'rails-footnotes', '~> 4.0' ``` And then just do the classic Ruby on Rails flow `bundle install` and following any gem specific install steps from it's own documentation.