Hot to Register Widget in WordPress by Hook
add_action( 'widgets_init', 'my_register_sidebar' );
function my_register_sidebar(){
register_sidebar(array(
'name' => 'My new sidebar',
'id' => 'your-sidebar-id',
'description' => 'My sidebar description',
'before_widget' => '<aside id="%1$s" class="widget group %2$s">',
'after_widget' => '</aside>',
'before_title' => '<h3 class="widget-title">',
'after_title' => '</h3>',
));
}