You must be logged on as an administrator or a member of the Administrators group in order to complete this procedure. If your computer is connected to a network, network policy settings may also prevent you from completing this procedure.
Open System in Control Panel.
On the Computer Name tab, click Change.
Under Member of, click Domain, type the name of the domain
you want to join, and then click OK. You will be prompted to
provide a user name and user password to join the computer to the
Click OK to close the System Properties dialog box.
You will be prompted to restart your computer to apply your changes.