You typically do not need to manually add a new computer in Active Directory. The first time a computer joins the domain, the computer will automatically be added to Active Directory. However, if for some reason you need to add a computer manually, follow these steps:

1. In Server Manager, select Tools > Active Directory Users and Computers.
2. In Active Directory Users and Computers, expand the name of the domain, right-click on the Computers folder, and select New > Computer.
3. In the New Object - Computer pop-up box, enter the name of a computer on the domain and select OK.

In this example, there is a computer on the network named workstation1. Workstation1 is added to Active Directory.