As I know little about how things work, do I just "include" the class - still don't know how to do that - and it all just "works"?
You include a class using the include preprocessor directive:
#include "Button.h"
Then, you need to create an instance of the class, with appropriate input data:
Button pushee(Some stuff goes here);
Then, you need to use various member of the instance to do various things. The Button class comes with examples that show how to use it.
So I'm guessing I only (bad choice of word there?) have to modify the "wait_on_escape" function to call the class?
You don't call a class. You call instance methods. Look at the Button examples.