Blocks

In the example you gave, you do not use one of the little buttons - they're designed for specific web-based services. Instead, you use the URL of that exact page - this may surprise you, but that page is not a HTML webpage, it is an Atom newsfeed. It has had stylesheets applied to make it appear like a normal webpage document.

"Feedburner" is one well-known service for providing newsfeeds so if you ever see a feedburner page which looks like that, you'll know it's actually a newsfeed. The only alternative is to use your browser's "View source" option (that's how I did it) but that requires you to be able to spot that it's not actually HTML code, which isn't necessarily easy...