php - How to add thumbnails to Wordpress recent posts widget? -

i have underscores theme , there widget "recent posts". need show posts thumbnails every post on widget. have enebled thumbnails in functions.php , uploaded them every post. have show these thumbnails in recent posts widget?

in functions.php have code

/**  * register widget area.  *  * @link http://codex.wordpress.org/function_reference/register_sidebar  */ function mytheme_widgets_init() {     register_sidebar( array(         'name'          => __( 'sidebar', 'fashiony' ),         'id'            => 'sidebar-1',         'description'   => '',         'before_widget' => '<aside id="%1$s" class="widget %2$s">',         'after_widget'  => '</aside>',         'before_title'  => '<h1 class="widget-title">',         'after_title'   => '</h1>',     ) ); } add_action( 'widgets_init', 'mytheme_widgets_init' ); 

i have no idea have include get_the_post_thumbnail(); want.