At the bottom of the UV Image Editor window, open the "UV" menu and click "Export UV Layout."

You will then get a "Save as" menu where you can specify where to save a PNG file. You can also change it to a different resolution or image type with the options in the lower left.

The default exported PNG image will have a grey outline of the UV map filled in with transparent white. The rest of the image is transparent so you can put it over top another image in a photo editor like GIMP and still see the image underneath. Good luck.

At the bottom of the "UV Image Editor" window, open the "UVs" menu and click "Export UV Layout."

You will then get a "Save as" menu where you can specify where to save a PNG file. You can also change it to a different resolution or image type with the options in the lower left.

The default exported PNG image will have a grey outline of the UV map filled in with transparent white. The rest of the image is also transparent so you can put it over top another image in a photo editor like GIMP and still see the image underneath. Good luck.