Moving a Selection

I have a picture of a horse on a white background in psd format which I want to drag into another psd image.
When I make the selection of the horse, then drag it into the other image it comes in o/k but still has a faint white replica of its original background.
Any suggestions to get rid of this welcome.
Norman Walsh

Try feathering the selection.

Norman, you might also try Layer>Matting>Defringe to see if that would help. There are always several ways to get something done if PS and everyone has their favorite ones.