I used Netbeans drag and drop design interface and it spit out this code: (I know some basic Java, but hardly any Swing or Jframe stuff, although I did read a few chapters from Dietel & Deitel book (actually, many chapters). Seems it should be pretty easy but I am not sure exactly how to go about it. The code it generated has setIcon() as part of a private function...I've looked up repaint? and others but the example they gave were not clear to me.

Code:
/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

/*
 * JavaImageAppUI.java
 *
 * Created on Jan 28, 2012, 6:26:33 PM
 */
package my.javaimageappui;

/**
 *
 * @author batman
 */
public class JavaImageAppUI extends javax.swing.JFrame {

    /** Creates new form JavaImageAppUI */
    public JavaImageAppUI() {
        initComponents();
    }

    /** This method is called from within the constructor to
     * initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is
     * always regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {

        jLabel1 = new javax.swing.JLabel();
        jButton1 = new javax.swing.JButton();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        jLabel1.setIcon(new javax.swing.ImageIcon("/home/batman/Desktop/Viper-Green.jpg")); // NOI18N
        jLabel1.setText("jLabel1");

        jButton1.setText("Next Image>");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
            }
        });

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(layout.createSequentialGroup()
                        .addGap(148, 148, 148)
                        .addComponent(jButton1))
                    .addGroup(layout.createSequentialGroup()
                        .addGap(62, 62, 62)
                        .addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 307, javax.swing.GroupLayout.PREFERRED_SIZE)))
                .addContainerGap(71, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addGap(38, 38, 38)
                .addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 219, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 56, Short.MAX_VALUE)
                .addComponent(jButton1)
                .addContainerGap())
        );

        pack();
    }// </editor-fold>

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:
//This is where I would like to add some code to change the photo
}

    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        /* Set the Nimbus look and feel */
        //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
        /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
         * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
         */
        try {
            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException ex) {
            java.util.logging.Logger.getLogger(JavaImageAppUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(JavaImageAppUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(JavaImageAppUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(JavaImageAppUI.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>

        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {

            public void run() {
                new JavaImageAppUI().setVisible(true);
            }
        });
    }
    // Variables declaration - do not modify
    private javax.swing.JButton jButton1;
    private javax.swing.JLabel jLabel1;
    // End of variables declaration
}
I figure I can make a function that does setIcon()? Not exactly sure to do it though. How do I add programming to change the image Viper-Green.jpg (to another image in same directory called Viper-Orange.jpg)?