Choose the appropriate link for your screen size from the options next to the wallpaper above. This will launch a browser window which contains your chosen picture at the relevant size.

Use the right-hand button on your mouse to select the picture, then pick the 'SET AS WALLPAPER' option from the menu which appears.

Choose the appropriate link for your screen size from the options next to the wallpaper above. This will launch a browser window which contains your chosen picture at the relevant size.

Press CTRL and then click on the image with your mouse. This will launch a menu. Select 'Download Image to Disk'. If you are offered a choice of where to download the image, select your desktop.

Open System Preferences and select Desktop, in the drop down menu select 'Chose Folder', navigate to the desktop and select 'Choose'. Select the image you wish to use, and it will appear on your desktop.