If you'd prefer to have Google+ Comments as the commenting system on your Ghost blog posts, that's really easy to do as well.

• Open Cyberduck and navigate to your theme folder.

• Select the post.hbs file to edit with your text editor

• Simply add this code to your post.hbs file after the {{/post}} tag, like I've done in the screenshot below:

  <section class="comment">
      <div class="g-comments" data-href="{{@blog.url}}{{url}}" data-first_party_property="BLOGGER" data-view_type="FILTERED_POSTMOD">Loading Google+ Comments ...
      </div>
      <script async type="text/javascript" src="//apis.google.com/js/plusone.js?callback=gpcb">
      </script>
      <noscript>Please enable JavaScript to view the <a href="https://plus.google.com/">comments powered by Google+.</a>
      </noscript>
  </section><br />

Now you need to open your Terminal or console and restart Ghost with the command:

$ service ghost restart

And you should get the following result on any blog post page: