Rails 4 search between created_at dates

I am a beginner in Ruby on Rails. I have a feedback model. I want to search the feedback database so that I get results within a selected date range using the created_at field. So I type e.g. "14/04/15" in one box and 16/04/15" and that when I click search, it brings up the @feedbacks between the typed dates, I will later on add jquery date-picker to select the dates in the text fields but I need the thing to function first.

I'm sorry if this has been answered before but nothing seems to help me. I have a form in my feedbacks index:

<%= form_tag(feedbacks_path, :method => "get") do %>
<%= text_field_tag :start_date, params[:start_date] %>
<%= text_field_tag :end_date, params[:end_date] %>
<%= submit_tag "Search", :name => nil %>
<% end %>

and this in my feedback controller:

 def index
 @feedbacks = Feedback.where("created_at >= :start_date AND created_at <= :end_date",
 {start_date: params[:start_date], end_date: params[:end_date]})
 @feedbacks = Feedback.where(user_id: current_user)
end

URL:

 http://localhost:3000/feedbacks?utf8=%E2%9C%93&start_date=14%2F04%2F2015&end_date=16%2F04%2F2015

Gemfile:

gem 'rails', '4.1.6'

ruby 2.1.3p242