According to this guide
http://technet.microsoft.com/en-us/library/ff817595(v=ws.10).aspx
RDP host server should NOT be the domain controller.
How then can this be set up using ONE machine? (not including the clients)
I'm new to server stuff and just learning as I go.
Don't set them up on the same operating system. You don't want anyone to have access to a domain controller other than trusted systems administrators. Ever.
If you really must use a single piece of hardware, what you should do is use some virtualization software to separate the roles into two separate server installs that run simultaneously, but are logically separate. Hyper-V Server or ESXi are the two largest players in the server virtualization market. I'd recommend one of them.