How to show error message on rails views?

I am newbie in rails and want to apply validation on form fields.

myviewsnew.html.erb

<%= form_for :simulation, url: simulations_path do |f|  %>

<div class="form-group">
  <%= f.label :Row %>
  <div class="row">
    <div class="col-sm-2">
      <%= f.text_field :row, class: 'form-control' %>
    </div>
  </div>
</div>
.....

Simulation.rb

class Simulation < ActiveRecord::Base
 belongs_to :user
 validates :row, :inclusion => { :in => 1..25, :message => 'The row must be between 1 and 25' }
end

I want to check the integer range of row field in model class and return the error message if it's not in the range. I can check the range from above code but not able to return the error message

Thanks in advance