add posts new action
add new_post file
modified posts form with changing url
add posts create action
add Post model
modified posts create action with params[:post] , saving and redirect to show page
add strong_parameter but that's not working, so add simple post_param for simplicity
add posts show action for displaying created post
add post show page
add posts index action
add posts index page
add posts link in welcome index
add new_post link in posts index
add back links in new and show pages of posts