AS2 Need help with timed button

Hello, I’m trying to make a flash game similar to “Dragon’s Lair” in which the animation flows until there’s a moment where you need to press a specified button in a short amount of time to progress, or it’s game over. I’m not very good with Flash programming (the only one I vaguely understand is AS2) so I’m turning for help to this forum.
I mostly do everything on frames and how I imagine it at the moment is like in this video:
When the animation arrives at a certain frame, an element will flash and display which button to press (WASD, not by clicking) and if the button isn’t pressed within a second (+/-) it disappears and leads to a frame labeled “GameOver_#”, but if it’s pressed it leads to frame labeled “Continue_#”, and so on until it reaches “Ending”. Basically a reflex game.
The problem is I don’t know how to make a button like that, so could anyone please help?