[jQuery] Live Example Question

[c19h28o2]

Hi,

On the jquery live examples site 
http://www.jquery.com/Tutorials:Live_Examples_of_jQuery
example B - which is 2 buttons which slide some text into and out of a
paragragh.

The code for the example is...

$("div.contentToChange p.firstparagraph:hidden").slideDown("slow");
$("div.contentToChange p.firstparagraph:visible").slideUp("slow");

I wanted to know how how this was setup on the HTML side?

Thanks