There are a multitude of ways in which you can import your photos or videos onto your computer, including the Photos app (on Mac or PC), using iCloud, downloading from Mail, syncing to Dropbox, or uploading your pictures to Google Photos.


How To Take Desktop Picture
In addition to creating pictures and storing them in a special folder, you can use your existing, or image library as a source of images for desktop wallpaper. Ever since OS X Leopard (OS X 10.5) the Mac has includes these libraries as pre-defined locations in the system’s Desktop & Screen Saver preferences pane. Although it’s easy to use these image libraries, it's a good idea to copying the pictures you intend to use as desktop wallpaper to a specific folder, independent of your Photos, iPhoto or Aperture library. That way you can edit images in any of the image libraries without worrying about affecting their desktop wallpaper counterparts.