Import Oracle DDL into Oracle Designer 9i?

I'm trying to find a way of importing ddl from oracle database into oracle designer to save me a hell of a lot of typing! I've heard it is possible. i created a .dmp file using oracle's export utility (with no data) and then tried to import it into oracle designer, I got the following error messages. Any ideas? I tried to google it but only returned one result, which was no help.

Connected to: Oracle9i Enterprise Edition With the Partitioning, OLAP and Oracle Data Mining options

Export file created by EXPORT:V09.02.00 via conventional path

Warning: the objects were exported by xxx, not by you

import done in WE8MSWIN1252 character set and AL16UTF16 NCHAR character set
import server uses WE8ISO8859P1 character set (possible charset conversion)
export client uses US7ASCII character set (possible charset conversion) . importing xxx's objects into CASEOWNER IMP-00033: Warning: Table "XTSYS_EXPORT_OBJECTS" not found in export file
IMP-00033: Warning: Table "XTSYS_IMPORT_IRID_MAPPING" not found in export file
IMP-00033: Warning: Table "XTSYS_IMPORT_IVID_MAPPING" not found in export file
IMP-00033: Warning: Table "XTSYS_TABS_EXPORTED" not found in export file
IMP-00033: Warning: Table "XTSYS_RM$REPOSITORIES" not found in export file
Import terminated successfully with warnings. Received on Tue Jul 18 2006 - 10:43:50 CDT