Having trouble with first GUI

This is my first whack at making a program that has an actually GUI instead of runing in the console. I'm having a hard time though. I'm reading through the stuff on oracle but I can't seem to get this to work. I'm trying to get it to display a window with said background.(Image is in the directory.) How can I make this work?
[Edit] Got in a hurry and forgot the code.]

Code:

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import java.awt.*;
import javax.swing.ImageIcon;
import javax.swing.*;



public class DisplayGUI {
               
        public DisplayGUI(){}
       
        public void showDisplay(){
               

                JFrame frame = new JFrame("blah blha asdfsadfd duurrrppp");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

                JMenuBar greenMenuBar = new JMenuBar();
        greenMenuBar.setOpaque(true);
        greenMenuBar.setBackground(new Color(154, 165, 127));
        greenMenuBar.setPreferredSize(new Dimension(200, 20));
       

        ImageIcon label = createImageIcon("Zexanima.jpeg");

       
        frame.getContentPane().add(label, BorderLayout.CENTER);
       
        frame.setSize(400,500);
        frame.setVisible(true);
        }



}

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Can you tell how you run it?

Quote:

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How can I make this work?

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you need to have a main() method in the class that you pass to the java command.