Change the desktop wallpaper in Windows 7

To change the desktop background (wallpaper), perform the following steps:
1. Click the Start button and then click Control Panel.
2. If the View by: is Category then click on Appearance and Personalization and then click Personalization. If the View by: is Large icons or Small icons then click on Personalization.
3. Click Desktop Background.
4. Choose your desktop background from the Picture Location: list or click Browse to select picture from your computer or from other sources.
You may also click Select all button to select all the pictures that are in Picture location.
5. Click Save changes.

Note:
You may add more than one picture to be as the desktop background. When you do this, Change picture every: list gets enabled and you can choose to change the pictures as specified in the Change picture every: list. You may also shuffle the pictures.