twitter bootstrap 3 - Will_paginate rails 4 not working with order('Created_at') -

i'm having issues getting will_paginate work here. i've tried couple different suggestions regarding controller keep getting number of different errors. basic question here how modify bit of code below in order "will_paginate" option work. i'm using bootstrap 3 , have entire controller , view posted below. thanks.

@pits = pit.order('created_at desc').group_by { |pit| pit.created_at.strftime("%b %y") } 

pits controller

class pitscontroller < applicationcontroller  def new   @pit = pit.new end  def index   @pit = pit.all   @user = user.find_by(params[:id])   @pits = pit.order('created_at desc').group_by { |pit| pit.created_at.strftime("%b %y") } end 

pit index.html.erb

<div class = "container list-pits">    <%= link_to "add new pit", new_pit_path, class: "btn btn-default" %>   <br>   <br>   <% @pit.each |pit| %>   <div class = "row">     <div class = "container">     <div class = "well pit-well">         <h3 id="pit-title"><%= link_to pit.topic, pit_path(pit) %></h3>        <p>by <%= link_to pit.author, '#' %></p>           <br>             <p><%= pit.summary %></p>             <p>replies (<%= pit.comments.count %>)</p>           <br>             <p>pit created by: <%= link_to pit.user.name, current_user %> on <%= pit.created_at %></p>             <%= link_to "join pit", '#', class: "btn btn-primary" %>           </div>     </div>       <% end %>    </div>  </div>