Hjælp til JFrame og JPanel

Kode 

import java.awt.*;
import javax.swing.*;
import java.awt.Color;

public class GUI extends JFrame
{
    private JFrame frame;

    private JPanel panel1, panel2, panel3;

    private JLabel label1, label2, label3;

    public GUI()
    {
        makeFrame();
    }

    public static void main(final String[] args)
    {
        GUI gui = new GUI();
    }

    public void makeFrame()
    {
        //Make the Frame
        JFrame frame = new JFrame("GUI");
        frame.setSize(1200,700);
        frame.setResizable(false);
        frame.setDefaultCloseOperatio(JFrame.EXIT_ON_CLOSE);
        frame.setLayout(new BorderLayout());

        //JPanels
        panel1 = new JPanel(new BorderLayout());
        panel2 = new JPanel(new BorderLayout());
        panel3 = new JPanel(new BorderLayout());

        panel1.setPreferredSize(new Dimension(1200, 350));
        panel2.setPreferredSize(new Dimension(1200, 350));
        panel3.setPreferredSize(new Dimension(1000, 250));
        panel1.setBackground(new Color(64,64,64));//darkGrey
        panel2.setBackground(new Color(255,0,0));//red
        panel3.setBackground(new Color(0,255,0));//green
        
        frame.add(panel1, BorderLayout.NORTH);
        frame.add(panel2, BorderLayout.SOUTH);
        panel2.add(panel3, BorderLayout.CENTER);

        panel1.setVisible(true);
        panel2.setVisible(true);
        panel3.setVisible(true);        
        
        //Set the Frame Visible
        frame.setVisible(true);
    }

    public void panel1()
    {
        label1 = new JLabel("jeg er label nr 1");
        label1.setBounds(5,5,50,50);
        add(label1);    
    }

    public void panel2()
    {
        label2 = new JLabel("jeg er label nr 2");
        label2.setBounds(5,5,50,50);
        add(label2);
    }
    
    public void panel3()
    {
        label3 = new JLabel("jeg er label nr 3");
        label3.setBounds(5,5,50,50);
        add(label3);
    }
}