Windows
1. Right-click the Desktop and choose Active Desktop > Customize My Desktop.
2. From the Background tab, choose Browse.
3. Select your preferred picture and click Open.
4. Click Apply.

Mac OS 9
Click on the desired Desktop Image link and drag the image to your desktop.
1. Control+Click the Desktop and select Change Desktop Background.
2. From the Desktop tab choose Place Picture.
3. Browse for your preferred picture on the desktop and click Open.
4. Click Set Desktop.

Mac OS X:
Click on the desired Desktop Image link and drag the image to your desktop.
1. Go to Apple Menu > System Preferences.
2. Click on the Show All icon to ensure all preferences are visible.
3. Click on the Desktop icon.
4. Select Choose Folder in the Collection drop-down menu. Navigate the desktop to find the image and click Choose. Select your preferred picture.