maybe this will help some people... but this is what i do...
i only download the original images... [click the options button on the download page]
then, all of the wallpapers i download go into one folder.
in the control panel/system preferences for the desktop/wallpaper,
there is always an option to add a folder that contain wallpapers.
add that folder and all the wallpapers in it will show up and you can pick and choose which wallpaper to use.
there should always be an option to "stretch to fit" or "shrink to fit" the wallpaper to your desktop resolution.
choose the appropriate one, press apply, and see how it looks.

this way, you can download wallpapers to your hearts content, store them all in one place, and then pick and choose which one to use based on your magic 8ball, the phases of the moon, solar flare activity, etc etc.

toodles,
harmless