Get the identifier for the current Workbooks property and add a worksheet to it. Then get the identifier for the new worksheet.
CREATEWS:
  call send (excelobj,'_getProperty',
            'Workbooks',
                    wbsobj);
  call send (wbsobj,  '_do',      'Add' );
  call send (excelobj,'_getProperty',
            'ActiveSheet',
                    wsobj );