There are just a couple of things you'll have to do in advance, in order to get your environment ready to be able to follow along. This takes about 30 minutes (of mostly waiting) so be sure to carve out some time to do this.
VirtualBox and Vagrant are two tools that we'll be using to emulate a production environment on your local machine. Install the latest version of VirtualBox from https://www.virtualbox.org/wiki/Downloads. Install Vagrant from http://www.vagrantup.com/downloads.html.
Once VirtualBox and Vagrant are installed, issue the following commands from Terminal:
vagrant box add precise32 http://files.vagrantup.com/precise32.box