NoMethodError simple_form_for in ruby on rails

<%= simple_form_for @post do |f| %>
  <%= f.label :title %>
  <%=f.text_field :title%>
  <%= f.label :phone %>
  <%=f.text_field :phone%>
  <%= f.label :description %>
  <%=f.text_field :description%>
  <%= f.submit%>
<% end %>

enter image description here how i can solve this

Make sure you've done the following:

• Added simple_form to your Gemfile
• Run bundle install
• Restarted your rails server

Then attempt this action again.