Below is a basic Active Directory installation for Windows 2012. The installation is a stand alone Active Directory infrastructure in which there is no current Active Directory domain in the environment.
Open Server Manager:
Select Add Roles and Features from the Configure this local server.
Select Role Based Feature, Select Next
Select a server from the server pool, then select the computer name of the machine to install the Active Directory 2012, Finally, select Next>
Select Active Directory Domain Services, Select Next>
Select Add Features
Watch the task bar to completion
Select Add a new forest, Enter <root domain name> then select Next
Select DNS, Enter the password and confirm password, then select Next
While it’s installing you can check the Dashboard and view the progress of the installation
After you select complete and the server reboots you will see all the new Active Directory tools installed in the Server Manager.