Jquery, novice to ninja, exercise files

Hey guys, i got the book, but i am confused about the exercise files.

They are already made, i was expecting the book, you would start out with a project and write it from the ground up, but then it starts with those files already, that’s already made, and its like i dont have to write anything for myself?

Or am i missed some other files? I hope you understand my confusion

The files are intended to give you a working example of what the book takes you through.