Create facebook share URL

Share your article in Facebook following code is used

<a href="http://www.facebook.com/sharer.php?u=<url to share>
&t=<title of content>" target="_blank"> link or image</a>

• url to share – what URL  you want to share to Facebook

• title of content – the title of what you are sharing

<a name="fb_share" type="button" 
   share_url="YOUR_URL">Compartir en Facebook</a> 
<script src="http://static.ak.fbcdn.net/connect.php/js/FB.Share" 
        type="text/javascript">
</script> 

For more http://developers.facebook.com/docs/share/