I'm sure I read somewhere on the W3C's Website about how you should do created and revised dates.

Think it was some markup or something you added around the dates itself that whould tell search engines that this was the date this document was created and the last time it was revised.

Does anyone how to do this?

And no, it wasn't meta data.

not for search engines there isn't

The date of document's last modification is normally handled by the webserver and it is given in Last-Modified HTTP header. No other way to put it down with HTML tags or whatever.