Update: a plugin adds the facebook like button for you
A very talented plugin developer has automated the whole process and by commenting below has alerted me to this plugin.
http://wordpress.org/extend/plugins/like
The video will remain so you can still see the how the process works but seriously the plugin is the best option.
A video tutorial 3min 22secs in length showing how easy it is to add a facebook like button to a regular post or page. This will allow viewers of the page or post to mention it on their facebook page driving more traffic and links to your website. Uses the facebook developers tool.
Link below is to tool that creates the code needed
http://developers.facebook.com/docs/reference/plugins/like
Link below is to tool that creates the code needed