In order to setup and configure backups for Active Directory on Windows Server 2008 a feature called windows server backup must be installed. NTBackup no longer exists in the new edition of server 08.
There are two sub features in Windows Server Backup, they are called Windows Server Backup and then you have the Command-line Tools. The command line tools are a set of cmdlets supplied from Powershell. Therefore you must install Powershell. After installing Windows Server Backup, navigate to the Administrative Tools Menu to launch the program or launch Server Manager and navigate to the Storage Node. In order to install Windows Server backup on a server running Server Core launch the following command from a command line C:\> ocsetup WindowsServerBackup .
Now that we have everything we need to perform a backup lets get started:
Method One

Method Two
To install Windows Server Backup on a Server Core installation run the following command from a command line.
Now that we have Windows Server Backup installed lets perform our first backup of Active Directory.

You have now backed up Active Directory successfully.
Backup Windows Server 2008 from the Command Line
If you want to script the backup process, or if you are backing up a server on a Server Core installation, you can use the WBADMIN.EXE command-line program. WBADMIN provides a complete set of options that perform essentially the same functions as the MMC snap-in, including managing backup schedules.