This tutorial is going to help you start off on the right foot by teaching you a few things that aren't Ruby. These things are, however, important to undestand for your future in the industry. If you are running MacOS or any flavor of Linux you are going to be very comfortable fitting into a Ruby workflow. Windows users will find that since so much of Ruby workflow is based on shell tools (and Windows has no real linux shell support) life is going to be a bit more interesting.
Furthermore all staff (and and an overwhelming majority of Rubyists) use OSX. If you are on windows either get dirty and start solving these problems for yourself or check out Rails Installer
OSX Users you could of course also use Rails Installer, however, as is true or so many things pre-packaged for you: this quick boost will be a net drag in the long-term. We would prefer that you build your environment yourself so that when it needs fixing you will better understand what is wrong.
To start we are going to download and install iTerm2. This terminal replacement for OSX is an industry standard with broader shortcut support and customisation options. You can download iTerm here. Install it to your Applications directory. This will be the application from which we run our shell commands. Welcome Home.
Lets install ruby!