Install Active Directory

After you gather information as described in "Gathering Installation Information" earlier in this guide, you can use the Active Directory Installation Wizard to install Active Directory..
Requirements

·         Credentials: local Administrator

·         Tools: Dcpromo.exe

To install Active Directory

1.       In the Run dialog box, type dcpromo and click OK.

2.       The Active Directory Installation Wizard appears. Click Next at the Welcome screen.

3.       For Domain Controller Type, select Additional domain controller for an existing domain. Click Next.

4.       For Network Credentials, enter the user name, password, and domain for the user account that has permission to add this new domain controller to the domain. Click Next.

5.       Enter the name of the domain that you want the new domain controller to host. Click Next.

6.       For the Database and Log Locations, enter the paths for the locations of the directory database (Ntds.dit) and the log files. For better performance, store the database and log files on separate physical disk drives. Click Next.

7.       For the Shared System Volume, enter the path where you want to locate the system volume (SYSVOL). Click Next.

8.       Under Directory Services Restore Mode Administrator Password, enter the password that you want to use when you need to start Directory Services Restore Mode. Click Next.

9.       The Summary screen displays a list of the items you chose. Verify that the information is correct and then click Next to proceed with the installation.

10.    The wizard proceeds to install Active Directory. When it finishes, the wizard displays a summary screen listing the domain and site in which the new domain controller is a member. Note this information and ensure that it is correct. If the domain controller is not in the correct site, see "Performing Active Directory Post-Installation Tasks" earlier in this guide. Click Finish to close the wizard.

11.    Click Restart to restart the domain controller.

12.    Let the domain controller restart. If any message indicates that one or more services has failed to start, restart the domain controller one more time. If the initial replication cycles have not had enough time to complete during the first restart on a new domain controller, this can result in some services being unable to start successfully. If the message appears during additional restarts, examine the event logs in Event Viewer to determine the cause of the problem.

Ref: http://technet.microsoft.com/en-us/library/bb727062.aspx