LOL! YOu know, I still have my "Beginning ASP *2.0*" from 1998, and it has the *same* form and the same "calendar.asp" reference.
It was a dumb example. There isn't any "calendar.asp". They were just showing you how, in HTML, to construct a <form> that can be used to send information to a subsequent ASP page.
In my 2.0 book, the last sentence in that section that references Calendar.asp says, in part: "You won't be able to do anything with the information that you gather...".
SO, in short, keep reading. It does all get cleared up later in the book (probably in the same chapter).