How to create a sub-menu?

Hi,

I am trying to create a sub-menu for a card because the list of menu items might become to long.
I want to move the card to a certain location which has several spot to decide which one is being resolved first.
The main menu would say “Move to hangar” followed with a submenu of numbers which the hangar that it will be send to.
I am able to create the commands. I am able to create the initial sub-menu. What do not know is how to make the sub-menu items in your sub-menu resppond to a command you made