1. Navigate to the WordPress plugin directory of your development installation.
2. Create a new directory called ch10-book-review-widget.
3. Navigate to the directory and create a text file called ch10-book-review-widget.php.
4. Open the new file in a code editor and add an appropriate header at the top of the plugin file, naming the plugin Chapter 10 - Book Review Widget.
5. Add the following line of code to register a function to be called when widgets are initialized:

add_action( 'widgets_init', 'ch10brw_create_widgets' ); 

6. Add the following code segment to provide an implementation for the ch10brw_create_widgets function:

function ch10brw_create_widgets() { 
    register_widget( 'Book_Reviews' ); 
} 

7. Insert the following block of code to declare the Book_Reviews class along with its constructor method:

class Book_Reviews extends WP_Widget { 
    // Construction function 
    function __construct () { 
        parent::__construct( 'book_reviews', 'Book Reviews',
            array( 'description' =>                                     
                   'Displays list of recent book reviews' ) ); 
    } 
} 

8. Save and close the plugin file.
9. Navigate to the Plugins management page and Activate the Chapter 10 - Book Review Widget plugin.
10. Visit the Widgets section of the Appearance administration page to see the newly created Book Reviews widget appear as part of the list of Available Widgets.
11. Drag and drop the new widget to one of the available sidebars listed on the right-hand side to create a widget instance, and see that the widget currently has no available options to configure it: