Ruby on Rails routing error because of my root?

I just started using Ruby on Rails and I was following this guide and I was having trouble with 4.3 Setting the Application Home Page. It has you setting up the routes.rb like this -

Rails.application.routes.draw do
  get 'welcome/index'

  root 'welcome#index'
end

I have no idea what is wrong even tho it is simple, thanks for the help. ~Jimmy