Yup, the whole point of putting a `Like` button your page is so that site visitors can broadcast your page to their friends. However, to cause that broadcast to actually occur you have to put a bunch of Open Graph meta tags on your page and also (I think?) have a registered Facebook Application to go along with your site.

There's no place that's documented except for the developer forums.

For what it's worth, it's only five lines of meta tags that are well documented.