I just don't get Javascript

First, I want to say that my textbook doesn't explain jack ****.
I have an assignment in my HTML class that requires me to use javascript. One line says:
"declare a variable named 'rNum' which is equal to a random integer between 1 and the value of the size variable"

I have no idea what I'm supposed to do in order to achieve this.:confused: I am completely lost and starting to hate the person who wrote my textbook. Can anyone help?

It's tricky to help without telling the answer so I'll just point to some webpages that should help.

To declare a variable:

http://www.w3schools.com/js/js_variables.asp

To get a random integer:

http://www.pageresource.com/jscript/jrandom.htm

Hopefully those are better than your book

david_kw