To Install Ruby on Mac:

Install xcode :

$ xcode-select --install

Install Homebrew :

$ ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

Install Ruby version manager(RVM) :
$ \curl -sSL https://get.rvm.io | bash -s stable

Install ruby with RVM :
$ rvm install ruby-head

Install version 2.3.1 ruby :

$ rvm install 2.3.1
$ rvm --default use 2.3.1

Hope this helps, (see the instructions to install ruby on Windows machine in youtube demo video comments section)