wp_nav_menu from horizontal to vertical?

Hi there,

I have a problem with wp_nav_menu. The code below is for a horizontal wp_nav_menu, but i want it to be vertical… how can i do this??

Thnx for the help

in the header.php:

<div id="navigation" class="clearfix">
            <?php
            //define main navigation
            wp_nav_menu( array(
                'theme_location' => 'menu',
                'sort_column' => 'menu_order',
                'menu_class' => 'sf-menu',
                'fallback_cb' => 'default_menu'
            )); ?>
        </div>

in the css:
[CSS moderated as per the Forum Rules. Please just post a link to your site.]

[No bumping. If it’s that urgent, consider hiring someone.]