1, Create a role

e.g. Create role leonard905;

2, Grant privilege to role

e.g. GRANT create session, create database link TO leonard905;

3, Grant role to users.

e.g. GRANT leonard905 to Jack, Bob, Cathy;

If you want to users also have the right to grant privileges in the role to other users, then

GRANT leonard905 to Jack, Bob, Cathy WITH ADMIN OPTION;

Hope this helps.