Hmmm, not really sure how to do what you are talking about. Maybe I am misunderstanding though. Could you maybe clarify a bit please? Maybe some screens will help.
The Base layer is this.
The second one is my "Oval"
The third one introduces the screenshot. Using my desktop for example.
The fourth one shows the problem I am having.
I am wanting to have the screenshot come through the center of that oval. Other then that, I don't want any of the screenshot showing.
Hope this helps.
Sorry about the size.