For Internet Explorer / Firefox
1. Select “Wide” or “Standard” according to your desktop size and click one of the resolution files.
2. The wallpaper will appear in a new window. Right click on the image (For Macintosh, press control and click), select “Set as wallpaper/Set as desktop preferences”.
For Macintosh Safari
Complete step 1 & 2 above, then press control and click.Select “Save image on desktop”, set image as wallpaper via “System Preferences” then “Desktop and screen-savers”.