Click the size that matches your screen resolution and the image will appear in a separate browser window. Then follow the instructions below for your computer's operating system: -

Windows
Right-click over the large image that has appeared in the separate browser window and select "set as background" or "set as wallpaper".

Apple Mac
Ctrl+click over the large image that has appeared in the separate browser window and select “Save Image As” or “Download Image to Disk” and save it to your hard drive.

Go to the Apple menu and select the Desktop tab in the Appearance control panel (or Desktop Pictures >> Picture tab for OS8 or above).  Click “Remove Picture” to remove your old wallpaper.

Then click “Select Picture” to select the DigiNature image you just saved.  Click “Set Desktop” and close the window.