i think youre looking for the `register_sidebar`function.

    if ( function_exists('register_sidebar') )
      register_sidebar(array(
        'name' => 'Name of Widgetized Area',
        'before_widget' => '<div class = "widgetizedArea">',
        'after_widget' => '</div>',
        'before_title' => '<h3>',
        'after_title' => '</h3>',
      )
    );

with this you get a new WidgetArea in the widget section in the backend.

You would then need to choose where you want it to appear. For example, if you would want it somewhere in the header, add this there, with this could:

    <?php if ( !function_exists('dynamic_sidebar') || !dynamic_sidebar("Name of Widgetized Area") ) : ?>
    <?php endif;?>