You can read the introduction page. If you are curious and want to learn more about RoR, then proceed to learn the whole tutorial to RoR.
Getting Started with Rails - Ruby on Rails Guides
Read the whole article. It's very useful and will help you build a sample application in rails to get to know how it all works. It is not compulsory but it will be an added advantage if you know how to build something before you go ahead and try to secure it.
Ruby on Rails Tutorial | A Complete Guide To Ruby On Rails - HKR
An easier guide to follow with to-the-point instructions. You can quickly get up to speed on RoR using this tutorial.