Como colocar uma imagem em uma JLabel e Jlabel em um JFrame

import java.awt.Component;
import java.awt.Dimension;
import java.awt.Toolkit;

import javax.swing.ImageIcon;
import javax.swing.JPanel;
import javax.swing.JFrame;
import javax.swing.JLabel;
import java.awt.Panel;
import java.awt.GridBagLayout;
import java.awt.Rectangle;

public class MenuPrincipal extends JFrame {

	private static final long serialVersionUID = 1L;
	private JPanel jContentPane = null;
	private Panel panel = null;
	private JLabel labelImage = null;
	
	public MenuPrincipal() {
		super();
		initialize();
	}

	private void initialize() {
		this.setSize(800, 600);
		this.setContentPane(getJContentPane());
		jContentPane.setVisible(true);
		labelImage.setVisible(true);
		this.setTitle("JFrame");
		centerWindow(this);
		this.add(labelImage);
	}

	private JPanel getJContentPane() {
		if (jContentPane == null) {
			labelImage = new JLabel();
			labelImage.setText("");
			labelImage.setBounds(new Rectangle(7, 456, 790, 566));
			ImageIcon logo = new 

ImageIcon(this.getClass().getResource("/tela.JPG"));     
		    labelImage = new JLabel(logo);
			jContentPane = new JPanel();
			jContentPane.setLayout(null);
			jContentPane.add(getPanel(), null);
			jContentPane.add(labelImage, null);
			jContentPane.add(labelImage, null);
		}
		return jContentPane;
	}
	
	public void centerWindow(Component frame)  
	{  
	    Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();  
	    Dimension frameSize = frame.getSize();  
	      
	    if ( frameSize.width > screenSize.width )  
	        frameSize.width = screenSize.width;  
	      
	    if ( frameSize.height > screenSize.height )  
	        frameSize.height = screenSize.height;  
	      
	    frame.setLocation ( (screenSize.width - frameSize.width ) >> 1, (screenSize.height - 

frameSize.height) >> 1 );  
	}
	private Panel getPanel() {
		if (panel == null) {
			panel = new Panel();
			panel.setLayout(new GridBagLayout());
			panel.setBounds(new Rectangle(0, 0, 792, 0));
		}
		return panel;
	}

}