create rb segment

what is the command to create a rollback segment in a tablespace X and provide storage parameters to it..?Thanks

CREATE ROLLBACK SEGMENT RBS_01 TABLESPACE RBS
STORAGE ( INITIAL 10240K NEXT 10240K OPTIMAL 102400K MINEXTENTS 4 MAXEXTENTS 400);

ALTER ROLLBACK SEGMENT RBS_01 ONLINE;

Modify your init.ora to include this rbs (if RBS is private)