Windows:

1. Click on the correct resolution for your monitor size (to check this, right click on your desktop and select the "Properties" then choose the "Settings" tab).
2. Allow the image to fully load on the new window.
3. Right-click onto the image, a pop-up window will show up.
4. Select "Set as Wallpaper" or "Set as Background."
5. Your new wallpaper should appear on your desktop.

Mac OS X:

1. Click on the correct resolution for your monitor size (to check this, click on the Apple menu and select "System Preferences..." > "Display").
2. Allow image to fully load on the new window.
3. Control-click and select "Save Image to the Desktop."
4. From the Apple menu > "System Preferences..." > "Desktop."
5. Drag the downloaded image onto the "Current Desktop" image in the window. Go to "Choose Folder" and select Desktop and navigate the new image.
6. Your new wallpaper should appear on your Desktop.

Mac OS 9.0:

1. Click on the correct resolution for your monitor size (to check this, click on the Apple menu and select "Control panel").
2. Allow image to fully load on the new window.
3. Control-click and select "Save this Image as" or "Download Image to Disk", saving the image to your desktop.
4. From the Apple menu, open the "Control Panel" > "Appearance" and click the "Desktop" tab.
5. Click "Place Picture" and use the dialog box to load the wallpaper from the desktop. Press "Open."
6. Choose "Position Automatically" from the position pop-up menu.
7. Click "Set Desktop."
8. Your new wallpaper should appear on your Desktop.