To be able to create tables in a user's own schema, the user needs to have the CREATE TABLE privilege, or the CREATE ANY TABLE privilege, which is more powerful, and allows the user to create tables in other user's schema. The following tutorial exercise gives you a good example on CREATE TABLE privilege:

>.insqlplus /nolog

SQL> CONNECT DEV/developer

SQL> CREATE TABLE ggl (id NUMBER);

ORA-01031: insufficient privileges

SQL> disconnect

SQL> connect SYSTEM/globalguideline

SQL> GRANT CREATE TABLE TO dev;

Grant succeeded.

SQL> disconnect

SQL> CONNECT DEV/developer

SQL> CREATE TABLE ggl (id NUMBER);

ORA-01950: no privileges on tablespace 'SYSTEM'

The above error message tells that user "dev" is not allowed to use the tablespace "SYSTEM". See the next question for answers.