It would help if you'd of told us which blog platform your using, I'm assuming your using wordpress? If so, just search "Facebook" in plugins and you'll find loads of differnet plugins, unless your on about importing your blogs posts to your facebook account (Via notes), then you need to go to notes and import via xml/rss or something like that, can't remember exactly, but it's facebook, so it's pretty simply explained.
Are you using Wordpress, or Blogger, or something else? It would be great to know which platform so a reasonable answer can be given. If it's Wordpress, you can go to the plugin repository and just search for Facebook (or perhaps FB).