Add Widgets in wordpress

add_theme_support('customize-selective-refresh-widgets');
function twentyfifteen_widgets_init()
{
    register_sidebar(array(
        'name' => __('Widget Area', 'twentyfifteen'),
        'id' => 'sidebar-1',
        'description' => __('Add widgets here to appear in your sidebar.', 'twentyfifteen'),
        'before_widget' => '<aside id="%1$s" class="widget %2$s">',
        'after_widget' => '</aside>',
        'before_title' => '<h2 class="widget-title">',
        'after_title' => '</h2>',
    ));

}

add_action('widgets_init', 'twentyfifteen_widgets_init');


// Frontend

 <?php if (!function_exists('dynamic_sidebar') || !dynamic_sidebar('footer1')) ?>