Insert a JPanel with null layout into a JScroll

I have a JPanel (myPanel) with a lot of button inside (this panel is contained in another panel that contain other components). I would insert this JPanel (myPanel) into a scroll to control better the button.

This is a part of my code:

    JPanel firstPanel = new JPanel(null);
    ......
    ......        
    JPanel myPanel = new JPanel(null);
    myPanel.setBounds(0, position+22, 400, 500);
    for (int i=0; i<size; i++) {
        JButton button = new JButton(myList.get(i));
        if (counter%4 == 0) {
            button.setBounds(270, 0+(4*i), 90, 18);
        } else if (counter%3 == 0) {
            button.setBounds(180, 4+(4*i), 90, 18);
        } else if (counter%2 == 0) {
            button.setBounds(90, 8+(4*i), 90, 18);
        } else {
            button.setBounds(0, 12+(4*i), 90, 18);
        }
        myPanel.add(bottone);
     }
     ......
     ......
     firstPanel.add(myPanel);

So, how can i do to insert it into a scroll?