Mac Users:
Changing your desktop picture is quite simple. Just follow these instructions.
1. Click on the image that you want to save and hold down the mouse button until a menu pops up.
2. Select "Download image to disk"
3. Save the file in a place that you'll remember where to find it. The "appearance" folded under the system folder is probably the best place for desktop pictures.
4. Go under the apple menu and scroll down to the control panels.
5. Slide over to the appearance menu.
6. Click on "Place Picture"
7. Select the photo that you just downloaded and click save or select.
8. Click on "set desktop" and you're done.
Windows Users:
Changing your desktop wallpaper is quite simple. Just follow these instructions.
1) Download the correct size of wallpaper that you want. Save it somewhere on your disk where you can easily remember and find. My Documents or My Pictures is a good place to save.
2) Right-Click on an empty part of your screen where there are no windows open or icons.
3) Select "Properties" from the menu that appears
4) Click on "Background" at the top of the box that appears
5) Click on the "Browse" button and then browse to your desired wallpaper image
6) Click OK and you'll notice your background image has changed to the picture you selected