You are same as me, the people use dcpromo to install Active Directory Services. Unfortunately you can no longer do that in Windows Server 8 Beta. You will receive a message “The Active Directory Services installation Wizard is relocated in Server Manager.” if you type dcpromo in command prompt.
You can use Server Manager to install Active Directory Services like the video below.
This is not the end yet. You need to click on the exclamation mark and choose Promote this server to a domain controller to complete the installation indeed.
Note: You must have a static IP address and add DNS Server before promote the server to a domain controller.