URL structure -> www.my-site.com/menu/submenu

[eluser]borgir[/eluser]
Hi there!
Let's suppose I have a menu and submenu (each one in a separate controller) and I want to make something like:
www.my-site.com/menu/submenu
How can this be accomplished?
And finally, how can I use inheritance in this files?
I've made something like

Code:

class Submenu extends Menu {

}

but it gave me an error.
Thanks a lot!