Como chamar uma classe dentro do JInternalFrame?

new ActionListener() // anonymous inner class
         {  
            // display new internal window
            public void actionPerformed( ActionEvent event ) 
            {
               // create internal frame
               JInternalFrame frame = new JInternalFrame("Frame Interno", true, true, true,true);
               //JInternalFrame frame = new JInternalFrame();

               MyJPanel panel = new MyJPanel(); // create new panel
               frame.add( panel, BorderLayout.CENTER ); // add panel
               frame.pack(); // set internal frame to size of contents
               

               theDesktop.add( frame ); // attach internal frame
               try {
				frame.setMaximum(true);
				frame.setSelected(true);
			} catch (PropertyVetoException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
               frame.setVisible( true ); // show internal frame
            } // end method actionPerformed
         } // end anonymous inner class
      ); // end call to addActionListener
   } // end constructor DesktopFr