Why is the GUI not working, is the code correct?

Why is the GUI not working, is the code correct?

So Im trying to create 3 panels. The first panel has the layout set (e.g.
the radio buttons and next button) I`m now adding two new panels which
have different background colors. But when I execute the code I get an
error of Null point exception. How do I fix that?
Here is the code:
import java.awt.Color;import java.awt.event.ActionEvent;import
java.awt.event.ActionListener;import java.awt.CardLayout;import
javax.swing.*;public class Wizard {
private JLabel lblPicture;
private JRadioButton btLdap, btKerbegos, btSpnego, btSaml2;
private JButton btNext;
private JPanel panel;
private JPanel panelFirst;
private JPanel panelSecond;
CardLayout c1 = new CardLayout();
public static void main(String[] args) {
new Wizard();
}
public Wizard() {
JFrame frame = new JFrame("Wizard");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(600,360);
frame.setVisible(true);
MyPanel();
RadioButtons();
Button();
Image();
groupButton();
panel.setLayout(c1);
panelFirst.setBackground(Color.BLUE);
panelSecond.setBackground(Color.GREEN);
panel.add(panelFirst,"1");
panel.add(panelSecond,"2");
c1.show(panel,"panel");
frame.add(panel);
frame.pack();
frame.setVisible(true);
}
public void MyPanel() {
panel = new JPanel();
panel.setLayout(null);}public void RadioButtons() {
btLdap = new JRadioButton ("Ldap");
btLdap.setBounds(60,85,100,20);
panel.add(btLdap);
btKerbegos = new JRadioButton ("Kerbegos");
btKerbegos.setBounds(60,115,100,20);
panel.add(btKerbegos);
btSpnego =new JRadioButton("Spnego");
btSpnego.setBounds(60,145,100,20);
panel.add(btSpnego);
btSaml2 = new JRadioButton("Saml2");
btSaml2.setBounds(60,175,100,20);
panel.add(btSaml2);
}
public void Button() {
btNext = new JButton ("Next");
btNext.setBounds(400,260,100,20);
panel.add(btNext);
btNext.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
c1.show(panel, "2");
}});
}
public void Image() {
ImageIcon image = new ImageIcon("image.jpg");
lblPicture = new JLabel(image);
lblPicture.setBounds(200,20, 330, 270);
panel.add(lblPicture);
}
private void groupButton() {
ButtonGroup bg1 = new ButtonGroup( );
bg1.add(btLdap);
bg1.add(btKerbegos);
bg1.add(btSpnego);
bg1.add(btSaml2);
}
}