So I've completed the html/css tutorial set, and was wondering if theres something else I need to learn in order to be able to do something like whats at the top of the page here:

The part across the top of the screen with the "home, fanposts, fanshots" ect.  Is this not done through html/css?  I want to know how to make a thing like that across the top of a page and when each is hovered over, it drops down into options to select from.  If this isn't part of html/css, then that makes sense why I don't understand how to do it.