问Cloud 9 ruby on rails在撰写文章时出现错误

EN

<h1>  Create an article  </h1>
<%= form_for @article do |f| %>
<p>
<%= f.label :title %>
<%=f.text_field :title %>
</p>
<% end %>

class ArticlesController < ApplicationController    

def new
@article = Article.new  

end

end 

Rails.application.routes.draw do
# The priority is based upon order of creation: first created -> highest 
priority.
# See how all your routes lay out with "rake routes".
# You can have the root of your site routed with "root"
# root 'welcome#index'
root 'pages#home'
get 'about', to: 'pages#about'
resources :articles