DAVID BYRDEN
Facebook uses the Open Graph Protocol for metadata, so it's relatively simple for you to write.
OGP metadata goes in the <head> element of your web page. This element doesn't appear on the screen, but it contains information about your page. The Open Graph Protocol adds several <meta> elements to it. Here's an example:
<meta property="og:title" content="The thing I'm writing about" />
The values for 'property', such as "og:title", are names in XML namespaces. You'll have to declare those namespaces. Look at Facebook's worked example.
Finally, if you want a valid page, you'll have to change your DOCTYPE to HTML+RDFa.
Why do Facebook want metadata in your page?