Install the Windows Server Backup Tools for Windows Server 2008 (R2) following the instructions at http://technet.microsoft.com/en-us/library/cc732081%28WS.10%29.aspx.
For Windows Server 2008, refer to the http://technet.microsoft.com/en-us/library/cc753528%28WS.10%29.aspx article to obtain the instructions on how to perform a full backup of the server.
For Windows Server 2008 R2, refer to the http://technet.microsoft.com/en-us/library/cc753528.aspx article to obtain the instructions on how to perform a full backup of the server.