Fondo // Frame main

package APP;

import java.awt.BorderLayout;
import java.awt.EventQueue;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import java.awt.CardLayout;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.JLabel;
import java.awt.Color;
import java.awt.Font;
import javax.swing.JTextField;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.SystemColor;
import javax.swing.JSpinner;

public class Fondo extends JFrame {

    private JPanel contentPane;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    Fondo frame = new Fondo();
                    frame.setVisible(true);
                    frame.setSize(800,600);
                    frame.setResizable(false);
//                  Panel p = new Panel("/APP/fondo.jpg");
//                  frame.getContentPane().add(p);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    public Fondo() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 800,600);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        setContentPane(contentPane);
        contentPane.setLayout(null);

//      JPanel panel = new JPanel();
//      panel.setBounds(0, 0, 434, 262);

        Panel p = new Panel ("/app/fondo.jpg");
        p.setForeground(new Color(238, 232, 170));
        p.setBounds(0,0,800,600);
        contentPane.add(p);
        p.setLayout(null);

        JLabel lblElijaUnaInstancia = new JLabel("Elija Una Instancia");
        lblElijaUnaInstancia.setForeground(new Color(0, 0, 0));
        lblElijaUnaInstancia.setFont(new Font("Old English Text MT", Font.BOLD | Font.ITALIC, 60));
        lblElijaUnaInstancia.setBounds(129, 24, 726, 77);
        p.add(lblElijaUnaInstancia);

        JSpinner spinner = new JSpinner();
        spinner.setBounds(298, 112, 176, 134);
        p.add(spinner);
//      Panel panel = new Panel("/APP/fondo.jpg");
//      frame.getContentPane().add(panel);


        JPanel panel_1 = new JPanel();
        panel_1.setBounds(0, 0, 434, 262);
        contentPane.add(panel_1);

    }
}