Open DPM 2007 Administrator Console
Go the Management Window – Agents tab.
Select the Primary DPM server. Under the Details windows you will see the option Proteced computers enabled for Protection – Modify. Click on Modify.
In the View Details of Protected Computers Window select the server you want to backup, then click on Enable Secondary Protection. Enter the domain administrator credentials when prompted.
The Protection enabled status now change to Yes, click on Close. You are now ready to start backing up the resource.