The best way to learn Ruby is to dive in head first. Before any Ruby code will be discussed in this tutorial series, time will be spent getting the Ruby interpreter running, learning how to run Ruby scripts and how to examine their output.
You'll also have a chance to check out the interactive Ruby prompt. It's very convenient. It allows you to try new features immediately or experiment with Ruby without even having to open your text editor.
The best place to begin is by installing the Ruby interpreter on your computer.
Ruby Installation Guides: