Instructions
Click the "Start" button located on the bottom left of your desktop. Select "Control Panel" from the new window that will pop up.
Scroll through and select "Appearance and Personalization" in the Control Panel menu.
Click "Change Screen Saver" in the "Personalization" category in the Control Panel.
Click the drop-down box in the new window that opens up, and select "Photos" from the selections.
Click on "Settings," and select the folder and the picture from your computer's hard drive containing the photo you want to use as your screen saver.
Click on "Save" to close the settings window, then click on "Apply" and "OK" to save your new screen saver.