Hi, Lasio
I'm not certain if you wish to paste it into another layer on the same picture or if you want to capture it to use in another picture.
If you want it on a new layer in the same picture, do your selection with the lasso, when the dots are moving and you know it's selected, merely do Ctrl-C. This copies it to the clipboard.
To put it into another layer on the same picture, just do CTRL-V on the picture and it will go onto another layer. Or you can choose New layer at the bottom of your layer pallet and click in it and do the Ctrl-V.
Now, if you want to use your copy in a new picture. After you've selected it and copied it (with Ctrl-V or Edit/Copy) go to FILE. You'll see an entry for NEW FROM CLIPBOARD. Click on that and you'll find your picture in a new setting and can save it or do what you wish with it.
Sure hope this helps,
Lorace