3 Classes - GUI, ImageLoader and Wizard

GUI is the main frame whereas Wizard is just a popup that changes settings and imageloader is image handler

What I want is to load image from wizard to Jlabel on my main GUI but I have no idea where to start and never had experience with loading images onto GUI. Searching for answer on here didn't really help, it just create more confusion for me. I would appreciate if you also can add explanations as well.

GUI -

public class GUI extends JPanel{
   //variables
   JFrame frame = new JFrame("All-in-one Application");
   JMenuBar menuBar;
   JMenu file, edit, help, about;
   JMenuItem settings, startWizard, exit, save, load, readme;
   JLabel imgLabel;
   private Wizard wiz;
   

   public void topMenuBar(){
      
   //creating the menubar
   menuBar = new JMenuBar(); 
   //Menu
    file = new JMenu("File");
    edit = new JMenu("Edit");
    help = new JMenu("Help");
    about = new JMenu("About");
    
    //MenuItems 
    startWizard = new JMenuItem("Start Wizard");
     //listener for wizard
     Wizard wiz = new Wizard();
   //  GUIListener gListener = new GUIListener();
     startWizard.addActionListener(new ActionListener(){
         public void actionPerformed(ActionEvent e){
            wiz.startWizardd();
         }
     });
    
    settings = new JMenuItem("Settings");
    readme = new JMenuItem("Read Me");
    exit = new JMenuItem("Exit");
    save = new JMenuItem("Save");
    load = new JMenuItem("Load");
    

    //jbutton
   // test = new JButton("Test");

    //adding MenuItems to the Menu
   
    /**file**/
    file.add(startWizard);
    file.add(new JSeparator());
    file.add(save);
    file.add(load);
    file.add(new JSeparator());
    file.add(exit);
    //end file 

    //edit
    edit.add(settings);
    
    //help
    help.add(readme);
    //about
    
   //Adding Menu to the menu bar 
   menuBar.add(file);
   menuBar.add(edit);
   menuBar.add(help);
   menuBar.add(about);
   
 
   //exit action listener 
   exit.addActionListener(new ActionListener(){
      public void actionPerformed(ActionEvent e){
         System.exit(0);
      }
   });
  }
  
  public void mainPanel(){
  
    FlowLayout main = new FlowLayout();
    JPanel mainPanel = new JPanel();
    mainPanel.setLayout(main);  
    
    //jlabel
    imgLabel = new JLabel("img");
    
    
    mainPanel.add(imgLabel);
    
    frame.add(mainPanel, BorderLayout.CENTER);
  
  }
   
   
    //intiate GUI
   public void intGUI(){
     
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.setLocation(300,0);
      frame.setSize(1400,1000);
      topMenuBar();
      mainPanel();
      frame.setJMenuBar(menuBar);
    
      frame.setVisible(true);
   } 
}

Wizard:

public class Wizard extends JPanel{

   //variables 
    private ImageLoader imgload = new ImageLoader(this);
    private JButton applyButton, nextButton, backButton, cancelButton, openMapButton;
    JDialog wizDialog;
    JFrame wizFrame;
    JLabel siteNameLabel, siteMapLabel, AisleNumLabel, laneNumLabel, label; 
    JTextField siteNameField, aisleNumField, laneNumField;
    private JTextField mapURLField = new JTextField(20);
    JFileChooser chooser;
    private File file; 
    String fileName;
    BufferedImage img;   // private JPanel addInfoPanel, controlPanel;
     
    public void startWizardd(){
      System.out.println("Starting Wizard....");
       wizardGUI();
    }
    
    public void wizardCmpt()
    {
      
      //setting the panel up with gridlayout settings
      FlowLayout map = new FlowLayout();
      JPanel mapPanel = new JPanel();
      mapPanel.setLayout(map);
      
      FlowLayout grid = new FlowLayout();
      JPanel addInfoPanel = new JPanel();
      addInfoPanel.setLayout(grid);
      
      FlowLayout controls = new FlowLayout();
      JPanel controlPanel = new JPanel();
      controlPanel.setLayout(controls);
      
      
      //buttons
      JButton openMapButton = new JButton("Load Map");
      openMapButton.addActionListener(new ActionListener(){
         public void actionPerformed(ActionEvent e){
            imgload.fileChooser();
         }
     });
     
      
      JButton applyButton = new JButton("Apply");
      applyButton.addActionListener(new ActionListener() {
          public void actionPerformed(ActionEvent e) {
              
          }
      });
      JButton nextButton = new JButton("Next");
      JButton backButton = new JButton("Back");
      JButton cancelButton = new JButton("Cancel");
      cancelButton.addActionListener(new ActionListener(){
         public void actionPerformed(ActionEvent e){            
            wizFrame.setVisible(false);
            wizFrame.dispose(); 
         }
      });  
      
      //jlabels
      JLabel siteNameLabel = new JLabel("Site Name :");
      JLabel siteMapLabel = new JLabel("Site Map :");
      JLabel AisleNumLabel = new JLabel("Number of Aisles :");
      JLabel laneNumLabel = new JLabel("Number of Lanes :");
      
      //jtextfield
      JTextField siteNameField = new JTextField(5);
      JTextField aisleNumField = new JTextField(5);
      JTextField laneNumField = new JTextField(5);
      
      
      //adding to GUI  
      addInfoPanel.add(siteNameLabel);
      addInfoPanel.add(siteNameField);
      
      addInfoPanel.add(AisleNumLabel);
      addInfoPanel.add(aisleNumField);
      
      addInfoPanel.add(laneNumLabel);
      addInfoPanel.add(laneNumField);
      
     mapPanel.add(siteMapLabel);   
     mapPanel.add(mapURLField);   
     mapPanel.add(openMapButton);

      
      controlPanel.add(applyButton);
     // controlPanel.add(nextButton);
    //  controlPanel.add(backButton);
      controlPanel.add(cancelButton);
      
      wizFrame.add(addInfoPanel, BorderLayout.NORTH);
      wizFrame.add(mapPanel, BorderLayout.CENTER);
      wizFrame.add(controlPanel, BorderLayout.SOUTH);  
      
    }
    
 
    public void setMapUrlField(String text){
      mapURLField.setText(text);
    }
    
    public File getFile(){
      return file;
    }
          
    private void wizardGUI(){
            System.out.println("it's loading");
            wizFrame = new JFrame("Wizard Operation");
            wizFrame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
            wizFrame.setSize(600,600);
            wizardCmpt();
            wizFrame.pack();
            wizFrame.setVisible(true);          }  }

Image Loader:

public class ImageLoader{

   private JLabel label; 
   JFileChooser chooser;
   File file; 
   private BufferedImage img;
   private Wizard wiz; 
   
   public ImageLoader(Wizard wiz){
      this.wiz = wiz;
   }

   public File fileChooser(){
        File file = null;
        JFileChooser fileChooser = new JFileChooser();
        FileFilter imageFilter = new FileNameExtensionFilter("Image files ", ImageIO.getReaderFileSuffixes());
        fileChooser.setFileFilter(imageFilter);
        int retValue = fileChooser.showOpenDialog(wiz);
        if(retValue == JFileChooser.APPROVE_OPTION){
         file = fileChooser.getSelectedFile();
         wiz.setMapUrlField(file.getAbsolutePath());
        }else{
         wiz.setMapUrlField("");
      }
      return file;
    }
}