JComboBox And Parallel Array

I'm having an issue with using a JComboBox to select an item from a parallel array and displaying the correlating results in the same frame. Essentially, I have to add seven cities to a JComboBox drop down within a frame, select a city then display the population of that city in the frame with a label indicating the population. I have two issues:

1) my label text will not show up during execution unless I drag a corner no matter what width or height I make the frame.

2) I need to make the JComboBox selection correlate to the city population and display as a label, not having making that work using the getSelectedIndex() method.

I think I need to add an event listener for the combobox selection, not sure where to add that if that is the case. Here is my mess so far:

import java.awt.FlowLayout;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
public class JPopulation{
public static void main(String args[]) {

[Code] .....