public DisplayMainMenu() throws HeadlessException {
        //add variables
    final JFrame frame = new JFrame("Checker (menu)");
    final int numberOfSquares = 10;
    final int buttonTextSize = 25;
    final Dimension preferredSize =
        new Dimension(BoardAndMouse.SQUARE_SIZE * numberOfSquares, BoardAndMouse.SQUARE_SIZE * numberOfSquares);

    //create start button, first button
    JPanel startGamePanel = new JPanel();
    startGamePanel.setLayout(null);
    frame.add(startGamePanel);

    JButton startGameButton = new JButton("Start new game");
    startGameButton.setFont(new Font("Times", Font.PLAIN, buttonTextSize));
    startGameButton.setBounds(200,200, 220, 75); //x,y and then width and height
    startGamePanel.add(startGameButton);

    //create quit button, second button
    JPanel quitGamePanel= new JPanel();
    quitGamePanel.setLayout(null);
    frame.add(quitGamePanel);

    JButton quitGameButton = new JButton("Quit");
    quitGameButton.setFont(new Font("Times", Font.PLAIN, buttonTextSize));
    quitGameButton.setBounds(200,300, 220, 75); //x,y and then widht and height
    quitGamePanel.add(quitGameButton);

    //manage frame
    frame.setPreferredSize(preferredSize);
    frame.setResizable(false);
    //frame.setContentPane(menu); //make use of paintComponent in MainMenu

    frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    frame.setLocationRelativeTo(null);
    frame.pack(); //size the frame so all its content are at or above their preferred sizes
    frame.setVisible(true);

    }