Click Start - Run.
Type dcpromo press enter

Active directory installation wizard showing, click next.

click next.

Select domain controller for a new domain and click next.

Select domain in a new forest and click next.

Enter your full DNS name, click next.

Type netbios name, click next.

Click next. (If u want u can change database and log folder locations)

Click next.

Click next.

Select permissions compatible only with windows 2000 or windows 2003 os.

Type directory service restore password, click next.

Click next.



Click finish.

Click restart now.
After restart go to run and type DSA.MSC.

or

Go to Start - All programs - Administrative Tools - select Active directory users and computers.