Lynda.com – Build a ChildTheme

Hello guys,

I’m using wordpress 3.5.1 and in an exercise, the tutor talks about creating a functions.php file into the child theme like:
twentyten
functions.php
blabla subfolders
childoftwentyten
style.css

The goal is to change the header size, in his functions.php (the twentyten functions.php file and the functions.php in the child theme) screen:

define('HEADER_IMAGE_WIDTH', apply_fiters('twentyten_header_image_width', 940));
define('HEADER_IMAGE_HEIGHT', apply_filters('twentyten_header_image_height', 198));

He takes this portion and copy paste into the functions.php child theme.

My code is different in my wordpress (3.5.1), it is formulated this way:

function twentyten_setup() {

	//blabla stuff

	// The custom header business starts here.

	$custom_header_support = array(
		// The default image to use.
		// The %s is a placeholder for the theme template directory URI.
		'default-image' => '%s/images/headers/path.jpg',
		// The height and width of our custom header.
		'width' => apply_filters( 'twentyten_header_image_width', 940 ),
		'height' => apply_filters( 'twentyten_header_image_height', 198 ),
		// Support flexible heights.
		'flex-height' => true,
		// Don't support text inside the header image.
		'header-text' => false,
		// Callback for styling the header preview in the admin.
		'admin-head-callback' => 'twentyten_admin_header_style',
	);

	add_theme_support( 'custom-header', $custom_header_support );

	if ( ! function_exists( 'get_custom_header' ) ) {
		// This is all for compatibility with versions of WordPress prior to 3.4.
		define( 'HEADER_TEXTCOLOR', '' );
		define( 'NO_HEADER_TEXT', true );
		define( 'HEADER_IMAGE', $custom_header_support['default-image'] );
		define( 'HEADER_IMAGE_WIDTH', $custom_header_support['width'] );
		define( 'HEADER_IMAGE_HEIGHT', $custom_header_support['height'] );
		add_custom_image_header( '', $custom_header_support['admin-head-callback'] );
		add_custom_background();
	}

	// blabla stuff again

}

What portion of code do I have to copy paste to make it clean, as it is different from the tutorial example?
Thanks