To download a full-size image for your desktop / laptop background:
1. Right click on the image and select Open Image in New Tab.
2. From there, just drag and drop the image to your desktop! Alternately, you can right click again on the image in the new tab and click Save Image As... to your desktop.
3. Once it's on your desktop, right click again and select Set Desktop Picture!
Cheers,
College Hill