The official Getting Started with Rails guide contains a walk through the core concepts of building web applications with Ruby on Rails that can be completed without any previous experience.
It starts with how to create a new Ruby on Rails application, provides a step-by-step guide to build a simple e-commerce app and ends with getting it deployed to production.
It is possible to skip the installation of your local development environment and do the tutorial in your browser using the following link: https://rails-tutorial.evilmartians.io
Go check it out!