Add this to your functions.php file:

if (function_exists('register_sidebar')) {
  register_sidebar(array(
    'before_widget' => '<section id="%1$s" class="widget %2$s">',
    'after_widget' => '</section>',
    'before_title' => '<h1 class="widgettitle">',
    'after_title' => '</h1>',
  ));
}