Add Facebook comment box on wordpress blog

Edit themes=> single.php and findout following code

<?php the_content(' '); ?>

Add after


<b>Comment this on Facebook!</b>
<div id="fb-root"></div>
<script src="http://connect.facebook.net/en_US/all.js#xfbml=1"></script>
<fb:comments href="<?php the_permalink() ?>" num_posts="2" width="600"></fb:comments>