By default Microsoft active directory servers will offer LDAP connections over unencrypted connections (boo!).
The steps below will create a new self signed certificate appropriate for use with and thus enabling LDAPS for an AD server. Of course the "self-signed" portion of this guide can be swapped out with a real vendor purchased certificate if required.
Steps have been tested successfully with Windows Server 2012R2, but should work with Windows Server 2008 without modification. Will require both a system with OpenSSL (ideally Linux/OSX) and (obviously) a Windows Active Directory server.