1. Navigate to the ch2-page-header-output folder of the WordPress plugin directory of your development installation.
2. Open the ch2-page-header-output.php file in a text editor.
3. Add the following line of code to register a function to be called when WordPress first identifies that the requested page is an administration page:

add_action( 'admin_init', 'ch2pho_admin_init' );

4. Add the following code section to provide an implementation for the ch2pho_admin_init function:

function ch2pho_admin_init() {
    add_action( 'admin_post_save_ch2pho_options',
                'process_ch2pho_options' );
}

5. Add the following code section to provide an implementation for the process_ch2pho_options function that was declared in the previous step:

function process_ch2pho_options() { 
    // Check that user has proper security level
    if ( !current_user_can( 'manage_options' ) ) {
        wp_die( 'Not allowed' );
    }
 
    // Check if nonce field configuration form is present
    check_admin_referer( 'ch2pho' );
 
    // Retrieve original plugin options array
    $options = ch2pho_get_options();
 
    // Cycle through all text form fields and store their values
    // in the options array
    foreach ( array( 'ga_account_name' ) as $option_name ) {
        if ( isset( $_POST[$option_name] ) ) {
            $options[$option_name] =
                sanitize_text_field( $_POST[$option_name] );
        }
    }
 
    // Cycle through all check box form fields and set the options
    // array to true or false values based on presence of variables
    foreach ( array( 'track_outgoing_links' ) as $option_name ) {
        if ( isset( $_POST[$option_name] ) ) {
            $options[$option_name] = true;
        } else {
            $options[$option_name] = false;
        }
    }
 
    // Store updated options array to database
    update_option( 'ch2pho_options', $options );
 
    // Redirect the page to the configuration form
    wp_redirect( add_query_arg( 'page', 
                                'ch2pho-my-google-analytics',
                            admin_url( 'options-general.php' ) ) );
    exit;
}

6. Save and close the plugin file.
7. Click on the Settings section of the administration menu.
8. Click on the My Google Analytics menu item to display the configuration page.
9. Change the value of one of the fields and click on the Submit button.
10. When the page refreshes, you will see that the values displayed reflect the values submitted.