Invisible buttons

can someone help me learn how to make invisible buttons, like when you put your cursor over the button, sub buttons come down?

actions of frame 1

actions script of main buttons
on ([COLOR=royalblue]rollOver[/COLOR]) {

make the sub buttons into a movieclip
place the movie clip to frame [COLOR=red]x[/COLOR]

hopefully u’ll understand what i have just explained…

Goodweather~ God Bless

thank you:)