I am beginner in Rails.
In routes.rb I have
routes.rb
resources :posts
http://i.imgur.com/FlGROJC.png?1
when I click to \"Ad
That means that Rails is looking for posts/new.html.erb, and you don't have a posts/new.html.erb file. (Or haml file, or whatever templating language you're using.
posts/new.html.erb
You have
render "New"
in your controller. You should change it to:
render "new"