Another (but different!) menu question

I found part of the solution to my last question, so I deleted the post, but now I have another question. I'm using a horizontal dropdown menu with a horizontal submenu below it. How do I make it so that the submenu doesn't show up until I roll the mouse over one of the links? I'm more than a little lost as how to structure the onMouseOver, onMouseOut, and function hide() tags.

My code is here. Thanks for the help.
~Sarah