1. Start Enterprise Manager Console
2. Administrator = sysman
3. password = oem_temp
4. Management Server : Does it list any name there ? I guess not. Click the adjacent icon to add a new Management server. Add a name here (this name is actually the name of the service available in the tnsnames.ora so it should exactly match the service name; this is the service for the database that has your repository)

Let me know if this does not work.

- Rajeev