Implementar menu em interface grafica

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

public class AplicacaoPoupanca3 extends JFrame{

    private JTextField campoJuros, campoAnos, campoDeposito;
    private JLabel lbJuros, lbAnos, lbDeposito, lbTotal, lbResultado;
    private JButton ok;
    private JMenu menu;
    private JMenuBar barraMenu;
    private JMenuItem menuItem;

    public AplicacaoPoupanca3()
    {

        super("Poupex");
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setBounds(50,100,310,150);

        JPanel painel = new JPanel();



        menu = new JMenu();
        barraMenu = new JMenuBar();
        menuItem = new JMenuItem("Ajuda");

        barraMenu.add(menuItem);

        painel.setLayout(new GridLayout(5,2));
        this.getContentPane().add(painel);

        JPanel painela = new JPanel(new FlowLayout(FlowLayout.LEFT));
        JPanel painelb = new JPanel();

        lbJuros = new JLabel("Juros ao mês %:");
        campoJuros = new JTextField(15);

        painela.add(lbJuros);
        painelb.add(campoJuros);

        painel.add(painela);
        painel.add(painelb);


        JPanel painelc = new JPanel(new FlowLayout(FlowLayout.LEFT));
        JPanel paineld = new JPanel();

        lbAnos = new JLabel("Num. de anos:");
        campoAnos = new JTextField(15);

        painelc.add(lbAnos);
        paineld.add(campoAnos);

        painel.add(painelc);
        painel.add(paineld);


        JPanel painele = new JPanel(new FlowLayout(FlowLayout.LEFT));
        JPanel painelf = new JPanel();

        lbDeposito = new JLabel("Depósito mensal R$:");
        campoDeposito = new JTextField(15);
        painele.add(lbDeposito);
        painelf.add(campoDeposito);

        painel.add(painele);
        painel.add(painelf);


        JPanel painelg = new JPanel(new FlowLayout(FlowLayout.LEFT));
        JPanel painelh = new JPanel();

        lbTotal = new JLabel("Total poupado R$:");
        lbResultado = new JLabel("");

        painelg.add(lbTotal);
        painelh.add(lbResultado);

        painel.add(painelg);
        painel.add(painelh);

        JPanel painelj = new JPanel(new FlowLayout(FlowLayout.LEFT));

        ok = new JButton("OK");
        painelj.add(ok);

        painel.add(painelj);
    }

}