java.lang.NoClassDefFoundError

I am using JBuilder3.0 I don't understand the

Project properties.

Do you have to use this option. If yes, what do

you put there. I tried the following...

open project properties

click on set

navigate to my source file (my main())

click on my source file

click ok

when I run it I get the following error.

java.lang.NoClassDefFoundError.classes\FirstTest

Exception in thread main.

here is my code

import javax.swing.*;

class FirstFrame extends JFrame

{

public FirstFrame()

{

setTitle("FirstFrame");

setSize(300, 200);

}

}

public class FirstTest

{

public static void main(String[] args)

{

JFrame frame = new FirstFrame();

frame.show();

}

}

[843 byte] By [jeffroS] at [2007-9-26 19:24:27]