How add facebook like button

1. Create your App in facebook https://developers.facebook.com/apps

2.Copy and paste following code in your site after opening body tag and enter your App id

<script>
(function(d, s, id) {
  var js, fjs = d.getElementsByTagName(s)[0];
  if (d.getElementById(id)) {return;}
  js = d.createElement(s); js.id = id;
  js.src = "//connect.facebook.net/en_US/all.js#xfbml=1&appId=YOUR APP ID";
  fjs.parentNode.insertBefore(js, fjs);
}(document, 'script', 'facebook-jssdk'));
</script>

3.Paste following code in which place you need like button

<div class="fb-like" data-href="http://phpand.blogspot.com/" data-send="true" data-width="450" data-show-faces="true" data-font="arial"></div>

4. For more refer https://developers.facebook.com/docs/reference/plugins/like/