Duvidas com JButton

import java.awt.BorderLayout;

import java.awt.Color;

import java.awt.Container;

import java.awt.Rectangle;

import java.awt.event.KeyEvent;

import javax.swing.ImageIcon;

import javax.swing.JButton;

import javax.swing.JFrame;

import javax.swing.JLabel;

import javax.swing.JMenu;

import javax.swing.JMenuBar;

import javax.swing.JMenuItem;

import javax.swing.JPanel;

import javax.swing.JTextArea;

private static final long serialVersionUID = 1L;

private JMenuBar menuBarPrincipal = null;
private JMenu menuCadastrar = null;
private JMenu menuSair = null;
private JMenuItem menuItemCadastrarAlunoNovo = null;
private ImageIcon imageDeFundo = null;
private JPanel panelDeFundo = null;
private JLabel labeldeFundo = null;
private JButton buttonTeste = null;
	
public TelaInicial() {
	menuBarPrincipal = new JMenuBar();
	menuCadastrar = new JMenu("  Cadastrar  ");
	menuSair = new JMenu("  Sair  ");
	menuItemCadastrarAlunoNovo = new JMenuItem("Cadastrar Aluno Novo");
			
	menuCadastrar.add(menuItemCadastrarAlunoNovo);
	menuBarPrincipal.add(menuCadastrar);
	menuBarPrincipal.add(menuSair);
	setJMenuBar(menuBarPrincipal);
			
	exibirMenu();
	
	panelDeFundo = new JPanel();
	panelDeFundo.setOpaque(false);
	panelDeFundo.setLayout(null);
  	
	buttonTeste = new JButton("Teste");
	buttonTeste.setBounds(new Rectangle(250,200,70,30) );
	panelDeFundo.add(buttonTeste);			
		
	
	setGlassPane(panelDeFundo);
	getGlassPane().setVisible(true);
	
	Container c = getContentPane();
	c.setLayout(new BorderLayout());
	imageDeFundo = new ImageIcon("2007_school_escola.jpg");
	labeldeFundo = new JLabel(imageDeFundo);
	c.add(labeldeFundo, BorderLayout.CENTER);
	
}

public void exibirMenu() {		
	setSize(640, 480);
	setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	setTitle("Controle Acadêmico");
	setLocationRelativeTo(null);
	setVisible(true);		
	
}