Creating Database Users 
Prerequisites
The database is in the ONLINE operational state.
You are logged on to the database as database system administrator or as a database user of the DBA user class.
Procedure
This function has not been implemented in Database Studio yet. Use the corresponding SQL statement instead.
More information:
SQL Reference Manual, SQL Statements Overview
Result
The current user becomes the owner of the database user.
More Information
Database Administration, Database Users