Fortigate DNS Server Setup

Hi,

I'm trying to setup a Fortigate firewall.. there's a local domain controller and I need to setup DNS internally.

Is there a step-by-step guide?  I still want the Fortinet DNS servers to be used but I want the Fortigate DHCP/DNS server to respond to internal requests.

How do I setup a domain and domain controller entries on DNS.

Thanks!

Paul