ASP pages are made with 2 interconnected parts: The server side code of ASP will be enclosed special tags, < % % > brackets.
< %Anything inside these tags will be ran by the server before running or posting html. % > For instance, if you look at the source code for the intro.aspx page, you'll see that everything in those brackets isn't written in HTML: it's written in another language, Visual Basic.

Using If and ElseIf in visual basic, I can make different parts of the HTML disapear.