Pokud ti jde jenom o vykreslení obrázku do JPanel, tak nejjednodušeji asi takto:

import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class ImagePanel extends JPanel {

	private BufferedImage image;

	public ImagePanel() {
		try {
			image = ImageIO.read(new File("c:/apple.jpg"));
		} catch (IOException ex) {
			// handle exception...
		}
	}
	
	public BufferedImage getImage() {
		return image;
	}

	@Override
	public void paintComponent(Graphics g) {
		g.drawImage(image, 0, 0, null); 
	}
	
	public static void main(String[] args) {
		final JFrame f = new JFrame();
		ImagePanel image = new ImagePanel();
		f.getContentPane().add(image);
		f.pack();
		f.setSize(351,400);
		
		SwingUtilities.invokeLater(new Runnable() {
			@Override
			public void run() {
				f.setVisible(true);				
			}
		});
	}
}