You can choose a picture that will be associated with your user account and shown on screens or menus that display your user name, such as the Welcome screen or Start menu.
Open User Accounts by clicking the Start button , clicking Control Panel, clicking User Accounts and Family Safety (or clicking User Accounts, if you are connected to a network domain), and then clicking User Accounts.
Click Change your account picture.
Click the picture you want to use, and then click Change Picture.– or –If you want to use a picture of your own, click Browse for more pictures, navigate to the picture you want to use, click the picture, and then click Open. You can use pictures of any size, but they must have one of the following file name extensions: .jpg, .png, .bmp, or .gif.