(1) you must be logged in as SYS with SYSDBA privilege invoked. (2) you must have edited initmynewdb.ora file to spawn an oracle instance (3) and you started the oracle instance in nomount mode. (4) after the database is created you are also to create the medata and plsql packages Example
connect / as sysdba startup nomount pfile=$ORACLE_HOME/dbs/initmynewdb.ora CREATE DATABASE mynewdb USER SYS IDENTIFIED BY pz6r58 USER SYSTEM IDENTIFIED BY y1tz5p LOGFILE GROUP 1 ('/u01/oracle/oradata/mynewdb/redo01.log') SIZE 100M, GROUP 2 ('/u01/oracle/oradata/mynewdb/redo02.log') SIZE 100M, GROUP 3 ('/u01/oracle/oradata/mynewdb/redo03.log') SIZE 100M MAXLOGFILES 5 MAXLOGMEMBERS 5 MAXLOGHISTORY 1 MAXDATAFILES 100 MAXINSTANCES 1 CHARACTER SET US7ASCII NATIONAL CHARACTER SET AL16UTF16 DATAFILE '/u01/oracle/oradata/mynewdb/system01.dbf' SIZE 325M REUSE EXTENT MANAGEMENT LOCAL SYSAUX DATAFILE '/u01/oracle/oradata/mynewdb/sysaux01.dbf' SIZE 325M REUSE DEFAULT TABLESPACE tbs_1 datafile '/u01/oracle/oradata/mynewdb/tbs_1_01.dbf' SIZE 325M REUSE DEFAULT TEMPORARY TABLESPACE tempts1 TEMPFILE '/u01/oracle/oradata/mynewdb/temp01.dbf' SIZE 20M REUSE UNDO TABLESPACE undotbs DATAFILE '/u01/oracle/oradata/mynewdb/undotbs01.dbf'SIZE 200M REUSE AUTOEXTEND ON MAXSIZE UNLIMITED;
@?/rdbms/admin/catalog.sql @?/rdbms/admin/catproc.sql --- then create the required tablespaces --- then create users and assign quotas on the tablespaces to all those users.