Menu – Submenu

Hi.

So I have created a vertical menu, but as it is now, it’s just a one-level menu.

I want to modify it, so when you click on a link in the menu, a submenu rolls out, with the childpages for that given page. But i don’t know how to do this.

Anyone knows how it can be done or know a plugin, that allows you to do this?

I have an image here, wich illustrates what i mean:
http://www.phillip-sonderskov.dk/menu-submenu.jpg

Thanks in advance!

//Phillip