There are three things you can look into to realize something
First, Google a "Flash drop down menu tutorial" and learn how
to create one.
Next, figure out how to have one button (movieclip) tell the
other buttons (movieclips) but itself to disappear when you mouse
over that button, and reappear when you mouse out of the button.
You could use one function shared by all the buttons, wherein the
one that called the function is left alone.
Lastly look into Tweens to make the buttons that
disappear/reappear do so gradually rather than instantly. It could
be done using timeline animation as well, where each button
(movieclip) has a fade-out and a fade-in motion tween for its