|First, at least one of the computers must be running a server OS, such as Windows 2000 Server, Server 2003, or Server 2008. A client OS will not work. You would then promote the server to a domain controller with "dcpromo".|
There are many implications to setting up a domain. If you wish to proceed you should do some serious study, starting on the Microsoft website. You will not learn everything you need on any forum.