Java Programming

I made a simple calculator in java and I want to zip it up in an excutable jar file. I have 3 classes including my main in my .java file and am having trouble creating the jar archive. The source code for this program is:

import java.awt.*;
import java.awt.event.*;
import java.io.File;
import javax.swing.*;

// Frame for button panel
class CalculatorFrame extends JFrame
{
	public CalculatorFrame()
	{
		Toolkit kit = Toolkit.getDefaultToolkit();
		
		// sets title & icon image for window
		setTitle("Java Calculator v1.0 by D. Burkland");
		Image img = kit.getImage("calc.gif");
		setIconImage(img);	
		
		// add panel to frame
		CalculatorPanel calculator = new CalculatorPanel();
		add(calculator);
		pack();
		
		// centers frame 
		Dimension screenSize = kit.getScreenSize();
		int screenHeight = screenSize.height;
		int screenWidth = screenSize.width;
	
		// center & set dimensions of frame 
		setSize(width, height);
		setLocation(screenWidth / 3, screenHeight / 3);
		
		// set file chooser
		chooser = new JFileChooser();
		chooser.setCurrentDirectory(new File("."));
		
		// set up menu bar
		JMenuBar menuBar = new JMenuBar();
		setJMenuBar(menuBar);
		
		JMenu filemenu = new JMenu("File");
		JMenu helpmenu = new JMenu("Help");
		menuBar.add(filemenu);
		menuBar.add(helpmenu);
		
		// action of the exit text
		JMenuItem exitItem = new JMenuItem("Exit");
		filemenu.add(exitItem);
		exitItem.addActionListener(new
				ActionListener()
				{
					public void actionPerformed(ActionEvent event)
					{
						System.exit(0);
					}
				});		
		
		JMenuItem helpItem = new JMenuItem("About");
		helpmenu.add(helpItem);
		helpItem.addActionListener(new
				ActionListener()
				{
					public void actionPerformed(ActionEvent event)
					{
						JOptionPane.showMessageDialog(null, "Java Calculator By: D. Burkland Summer 2006");			
					}
				});
	}
	public static final int width = 350;
	public static final int height = 200;
	private JFileChooser chooser;
}

// Calculator panel
class CalculatorPanel extends JPanel
{
	public CalculatorPanel()
	{
		setLayout(new BorderLayout());
		
		result = 0;
		lastCommand = "=";
		start = true;
		
		// add the display
		display = new JButton("Hello");
		display.setEnabled(false);
		add(display, BorderLayout.NORTH);
		
		ActionListener insert = new InsertAction();
		ActionListener command = new CommandAction();
		
		// adds the buttons in a 4 x 4 grid
		calculator = new JPanel();
		calculator.setLayout(new GridLayout(4, 4));
		
		addButton("7", insert);
		addButton("8", insert);
		addButton("9", insert);
		addButton("/", command);
		
		addButton("4", insert);
		addButton("5", insert);
		addButton("6", insert);
		addButton("*", command);
		
		addButton("1", insert);
		addButton("2", insert);
		addButton("3", insert);
		addButton("-", command);
		
		addButton("0", insert);
		addButton(".", insert);
		addButton("=", command);
		addButton("+", command);
		
		add(calculator, BorderLayout.CENTER);
	}
	
	/**
	Adds a button to the center panel
	@param lable the button label
	@param listener the button listener 
	*/
	private void addButton(String label, ActionListener listener)
	{
		JButton button = new JButton(label);
		button.addActionListener(listener);
		calculator.add(button);
	}
	
	// Inserts the button action string to the end of the display 
	private class InsertAction implements ActionListener
	{
		public void actionPerformed(ActionEvent event)
		{
			String input = event.getActionCommand();
			if (start)
			{
				display.setText("");
				start = false;
			}
			display.setText(display.getText() + input);
		}
	}
	
	// Executes the command that the button action string demotes
	private class CommandAction implements ActionListener
	{
		public void actionPerformed(ActionEvent event)
		{
			String command = event.getActionCommand();
			
			if (start)
			{
				if (command.equals("-"))
				{
					display.setText(command);
					start = false;
				}
				else 
					lastCommand = command;
			}
			else 
			{
				calculate(Double.parseDouble(display.getText()));
				lastCommand = command;
				start = true;
			}
		}
	}
	
	// Carries out the pending calculation 
	public void calculate(double x)
	{
		if (lastCommand.equals("+")) result += x;
		else if (lastCommand.equals("-")) result -= x;
		else if (lastCommand.equals("*")) result *= x;
		else if (lastCommand.equals("/")) result /= x;
		else if (lastCommand.equals("=")) result = x;
		display.setText("" + result);
	}
	
	private JButton display;
	private JPanel calculator;
	private double result;
	private String lastCommand;
	private boolean start;
}

public class Calculator
{
	public static void main(String[] args)
	{
		CalculatorFrame calculator = new CalculatorFrame();
		calculator.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		calculator.setVisible(true);
	}
}

I am using Eclipse to create the jar files so if anybody has any advice I would be very grateful if you shared it.

Thanks,

Danny