1. Navigate to the ch11-hello-world folder of the WordPress plugin directory of your development installation.
2. Open the ch11-hello-world.php file in a text editor.
3. Add the following line of code at the end of the file to register a function to be called when the plugin is initialized:

add_action( 'init', 'ch11hw_plugin_init' ); 

4. Add the following code section to provide an implementation for the ch11hw_plugin_init function:

function ch11hw_plugin_init() { 
    load_plugin_textdomain( 'ch11hw_hello_world', false, 
                            dirname( plugin_basename( __FILE__ ) ) 
                            . '/languages' );  
} 

5. Locate the ch11hw_set_default_options_array function and add the same call to load_plugin_textdomain at the top of the function before the if statement:

load_plugin_textdomain( 'ch11hw_hello_world', false, 
                        dirname( plugin_basename( __FILE__ ) ) 
                        . '/languages' ); 

6. Save and close the plugin file.
7. Navigate to the Reglages menu to see if the plugin's menu item has changed.
8. Select the Bonjour Monde item to see the translated configuration page: