remove old routing definitions
update boards#index
update boards#create
update boards#update
update markup
update css
resources :comments
add CommentsController
rails g model comment board_id:integer from:string email:string content:text
add index
rake db:migrate
update boards#show
add comment form at boards#show
assoc Board and Comment
add validations
define comments#create
update boards#show
define comments#destroy
update markup
update css