Your Microsoft account name appears on the Start screen when you sign in to Windows 8 or Windows RT. It's the name that identifies you to your friends, family, coworkers and other people in Hotmail, SkyDrive, and other Microsoft apps and services. If you want to associate a different name with your Microsoft account, you only need to change it in one place.
Go to the Account summary webpage and sign in with your email address and password.
Under your name on the Overview page, tap or click Edit name.
Enter the first name and last name you want to use, and then tap or click Save.
The new name appears with your Microsoft account online, but it might not appear on the Start screen until you sign out of and back in to Windows.