Newbie question about GUI Designer - Doesnt work

Hello,

I have created a very simple form in GUI Designer and am now trying to put it into my main JFrame.

I did it the same way they do it in the help file but when i make an instance of my gui class I get this error:

Exception in thread "main" java.lang.NoClassDefFoundError: com/jgoodies/forms/layout/FormLayout

My gui class name is TestGUI and the code that causes this error is:

TestGUI test = new TestGUI();


Anyone know why this isnt working?

Any help would be greatly appreciated.

Thanks