New to Java - Need help

I'm working on an assignment that is supposed to be a Client and a Server in Java. I'm using JCreator to do this assignment. Instructions say that the Client program should be written to run as an applet that runs in a conventional browser.

I took the Client and Server example from the book and I hope to be able to modify it to fit my project needs.

My question is...

What is the difference bewteen

public class Client extends Applet

and

public class Client extends JFrame

My EXTREMELY limited knowledge of applets tells me I gotta use Applet to create a Client applet. But, what is JFrame? Why did they use that in the textbook? And can I transform it into an Applet?

ARRGGGGHHHH!!! I can't wait to graduate...two more weeks, two more weeks, two more weeks, two more...