Transparent edges on an elliptical Photo

Hello!

In a photo, I cut out an elliptical or round face.
I saved the cutted image as .; "New from clipboard"
No problem, the background is now transparent.

But now I want to make the edges of the oval or round image transparent.
(then I want to put the result image on another image)

How can I make the edges transparent with Corel Photo Paint (or Corel Draw)?

//Jan