I just didn't know how to word this but I cannot get it to work:
I have one image on top of another, the top image is called "Top".
When the mouse is down (or a finger is pressed on the touchscreen) I want to essentially draw "off" the top image revealing the bottom below. The draw line/brush thickness would be a predetermined size.
Adobe Director 12 on Mac OSX
So you're wanting to erase from the top image to reveal the lower one?
Yes, that is exactly what I'm looking to do.