Hi, Meera,
You can't directly track whether someone clicks a hotspot, and you can't directly track hovering. It'd be simpler to add the triggers directly to the captions.
Also, set the Initial state of caption 2 to Hidden. Then, on the layer revealed by caption 1, add a trigger that changes the state of caption 2 to Normal. Or you could even add that trigger to caption 1.
BTW, if any of the users might access the course on a mobile device, they'll get stuck, because there's no "hovering" on phones and tablets. So I suggest you have them click caption 1 to access that layer.
