Active Directory

Hello!
I new to server.I have some problem.
I Create a new domain tree in Active Directory from DCPROMO
Now i try  to create a child domain in Active Directory.
When i open dcpromo "This server is the last domain controller in the domain check box"
My question is how to add new child domain?
Thank you.

You need to do dcpromo on another pc. You can't do it on the same one. That's why you get that message about being the last dc. Running dcpromo on the pc that you already ran it from means you want to "delete" the dc. You'll only get the option for a new child domain if you run dcpromo on a different pc.

Thank you for quick reply !!!!