i'm expert on SQL Server, but new to Oracle world.
the oracle is installed on Windows 2000, if i need to do anything (backup, creation of new Shema, importing data...)it gives me that i have to use OMS .
i found that OMS needs sysman user,
or after searching i found that this username doesn't exist, maybe someone or the old DBA has deleted it.
i found on google search the below query to re-create the sysman user and i run it on my server, but i don't even have a tablespace called MGMT_TABLESPACE

create user SYSMAN identified by values 'xxxxxxxxxxxx'
default tablespace MGMT_TABLESPACE
temporary tablespace TEMP;

alter user SYSMAN quota unlimited on MGMT_TABLESPACE;

grant DBA to SYSMAN;
grant MGMT_USER to SYSMAN with admin option;
grant ALTER SESSION to SYSMAN;
grant ALTER USER to SYSMAN;
grant CREATE ANY TABLE to SYSMAN;
grant CREATE USER to SYSMAN;
grant DROP USER to SYSMAN;
grant SELECT ANY DICTIONARY to SYSMAN;
grant UNLIMITED TABLESPACE to SYSMAN;
grant READ on SYS.AUDIT_DIR to SYSMAN;
grant WRITE on SYS.AUDIT_DIR to SYSMAN;
grant DELETE on SYS.AUX_STATS$ to SYSMAN;
grant INSERT on SYS.AUX_STATS$ to SYSMAN;
grant SELECT on SYS.AUX_STATS$ to SYSMAN;
grant UPDATE on SYS.AUX_STATS$ to SYSMAN;
grant EXECUTE on SYS.DBMS_AQ to SYSMAN;
grant EXECUTE on SYS.DBMS_AQ_BQVIEW to SYSMAN;
grant EXECUTE on SYS.DBMS_JOB to SYSMAN;
grant EXECUTE on SYS.DBMS_LOB to SYSMAN;
grant EXECUTE on SYS.DBMS_LOCK to SYSMAN;
grant EXECUTE on SYS.DBMS_REDEFINITION to SYSMAN;
grant EXECUTE on SYS.DBMS_RLS to SYSMAN;
grant EXECUTE on SYS.DBMS_SHARED_POOL to SYSMAN;
grant SELECT on SYS.QT16228_BUFFER to SYSMAN;
grant SELECT on SYS.QT9774_BUFFER to SYSMAN;
grant SELECT on SYS.USER_TAB_COLUMNS to SYSMAN;



as a result user created, but many of the privileges that should be granted were ungranted such as MGMT_USER, AUDIT_DIR...

i need to split databse, i need to take backups, i need to be able to act as DBA

what to do? please help!!!