Moopartist,
If you wish to select the entire painting, go to Select>all, then Edit>copy. This will place it on the clipboard.
However, if you want to select only an object on the painting, try the selection brush or the lasso tool. You should see an outline around the selection once it is complete. Then, do Edit>copy. Now, open the blank file, then Edit>paste.
Refer to the program's help file for directions as they relate to the tools.
Sent from my iPad