Functions.php dosyasında ?> kodunun hemen üstüne alttaki kodu ekle.

//Adding the Open Graph in the Language Attributes
function add_opengraph_doctype( $output ) {
return $output . ' xmlns:og="http://opengraphprotocol.org/schema/" xmlns:fb="http://www.facebook.com/2008/fbml"';
}
add_filter('language_attributes', 'add_opengraph_doctype');

//Lets add Open Graph Meta Info

function insert_fb_in_head() {
global $post;
if ( !is_singular()) //if it is not a post or a page
return;
echo '';
echo '';
echo '';
echo '';
echo '';
if(!has_post_thumbnail( $post->ID )) { //the post does not have featured image, use a default image
$default_image="http://example.com/image.jpg"; //replace this with a default image on your server or an image in your media library
echo '';
}
else{
$thumbnail_src = wp_get_attachment_image_src( get_post_thumbnail_id( $post->ID ), 'medium' );
echo '';
}
echo "
";
}
add_action( 'wp_head', 'insert_fb_in_head', 5 );