Another Cropping Question!

GIMP is great, but......... the cropping function is not very customer-
friendly.  Here's the question:
I open an image, select the "ellipse selection tool" and mouse out  an
oval part of the image.  Now I have the original image with an oval
dotted area of the image that I want to keep.  How do I just keep and
save ONLY the oval area selected by the ellipse selection tool??  This
should be easy, but I can't figure it out!
Please comment.  Thanks.
EW