Auguste Rodin 

Mac (MAC O/S 8.0 – 9.1):
Once the image has fully loaded:
1: Move your cursor over the image.
2: Hold down the mouse button until a menu appears
3: Choose "save image as" and save image to your Mac's hard drive.
4: Open the control panel "Desktop Pictures"
5: Click remove picture, then click select picture
6: Load new wallpaper from where you saved the image on your computer
7: Finally, choose "position automatically" for wallpaper.

MAC (OS X) Wallpaper Instructions:
Once the image has fully loaded:
1: Move your cursor over the image.
2: Hold down the mouse button until a menu appears
3: Choose "Save Image to the Desktop" and save the image to your Computer's Desktop.
4: Go to Apple menu > System Preferences > Personal section and select "Desktop".
5: In the "Collection" menu on the left, go to "Choose Folder..." and locate the wallpaper image you have just saved on your Desktop.