Drop down menus

I’d like to add drop down navigation menus on the Primary Menu. I understand that I can simply indent desired sub-menu items in the menu editor to do this, but it seems like that requires the top-level item to link to an object (page, post, link, etc). I’m trying to make the top level menu item serve only to show the drop down, not to be an object itself. For example, say I want a Primary Menu with two items, “Foo” and “Bar”. I want to be able to expand “Foo” to see sub-menu items “Foo1” and “Foo2” beneath it, without “Foo” itself being an active link to anything. It sounds like I should add a new menu as an object to the Primary Menu, but I don’t see how to do that. Is this possible?

Disclaimer: this is my first web building attempt, so please don’t assume I have a lot of domain knowledge ??

Thanks.