The hostname or IP address of the target system must be entered in the Hostname of destination system field, and the Root password for destination system field should be filled in unless you have password-less SSH authentication setup.
By default the domain will be simply copied to the new system. However, the Action after transfer field can be used to have it moved instead, by deleting the server from the source system. This is necessary if both the source and destination share a clustered DNS server, or are secondary name servers for each other.