Customizing Your Windows 7 Background
Changing your desktop background in Windows 7 is simple. Right-click a blank area of the desktop and select Personalize. Click the Desktop Background link near the bottom of the Personalization window to open the Desktop Background window.
Choose a location from which to select a background picture in the Picture Location box, such as Windows Desktop Backgrounds or your Pictures library. If the location you want to use is not listed in the Picture Location list, click the Browse button to navigate to the correct folder.
Once you have found and selected an image to use as your Windows 7 background, stretch it by clicking the arrow under Picture Position and selecting Stretch, which will stretch the image to fit your screen. Other options include Fill, which also stretches the image to fit the screen but may crop the picture if the ratio is not the same as your screen; Fit, which fits the image to your screen using a dark border if the ratio is different; Tile, which uses smaller versions of the same image repeatedly, like tiles on a floor; and Center, which centers the image in the middle of the desktop with a border surrounding it.
After you have selected an image and setting for your Windows 7 background, click the Save Changes button to apply it.