Oracle initialization parameter Settings _oracle

The Oracle tutorial you are looking at is: Oracle initialization parameter settings. ALTER DATABASE DATAFILED:\ORANT\DATABASE\USER1ORCL. ORA RESIZE 1000M;
CREATE tablespace index_data datafiled:\orant\database\index_data SIZE 500M;
ALTER DATABASE DATAFILED:\ORANT\DATABASE\RBS1ORCL. ORA RESIZE 300M;
ALTER DATABASE DATAFILED:\ORANT\DASTABASE\TMP1ORCL. ORA RESIZE 300M;

Alter ROLLBACK segment "RB1" offline;
Alter ROLLBACK segment "RB2" offline;
Alter ROLLBACK segment "RB3" offline;
Alter ROLLBACK segment "RB4" offline;
Alter ROLLBACK segment "RB5" offline;
Alter ROLLBACK segment "RB6" offline;
Alter ROLLBACK segment "RB7" offline;
Alter ROLLBACK segment "RB8" offline;
Alter ROLLBACK segment "RB9" offline;
Alter ROLLBACK segment "RB10" offline;
Alter ROLLBACK segment "RB11" offline;
Alter ROLLBACK segment "RB12" offline;
Alter ROLLBACK segment "RB13" offline;
Alter ROLLBACK segment "RB14" offline;
Alter ROLLBACK segment "RB15" offline;
Alter ROLLBACK segment "RB16" offline;

Drop rollback segment "RB1";
Drop rollback segment "RB2";
Drop rollback segment "RB3";
Drop rollback segment "RB4";
Drop rollback segment "RB5";
Drop rollback segment "RB6";
Drop rollback segment "RB7";
Drop rollback segment "RB8";
Drop rollback segment "RB9";
Drop rollback segment "RB10";
Drop rollback segment "RB11";
Drop rollback segment "RB12";
Drop rollback segment "RB13";
Drop rollback segment "RB14";
Drop rollback segment "RB15";
Drop rollback segment "RB16";

Create rollback segment "RB1" tablespace "Rollback_data" Storage (initial 1m next 1m);
Create rollback segment "RB2" tablespace "Rollback_data" Storage (initial 1m next 1m);
Create rollback segment "RB3" tablespace "Rollback_data" Storage (initial 1m next 1m);
Create rollback segment "RB4" tablespace "Rollback_data" Storage (initial 1m next 1m);
Create rollback segment "RB5" tablespace "Rollback_data" Storage (initial 1m next 1m);
Create rollback segment "RB6" tablespace "Rollback_data" Storage (initial 1m next 1m);

Alter ROLLBACK segment "RB1" online;
Alter ROLLBACK segment "RB2" online;
Alter ROLLBACK segment "RB3" online;
Alter ROLLBACK segment "RB4" online;
Alter ROLLBACK segment "RB5" online;
Alter ROLLBACK segment "RB6" online;

ALTER DATABASE add logfile C:\orant\database\log1.ora size 10m;
ALTER DATABASE add logfile C:\orant\database\log2.ora size 10m;
ALTER DATABASE add logfile C:\orant\database\log3.ora size 10m;
ALTER DATABASE add logfile C:\orant\database\log4.ora size 10m;
ALTER DATABASE drop logfile C:\orant\database\log1orcl.ora;
ALTER DATABASE drop logfile C:\orant\database\log2orcl.ora;
ALTER DATABASE drop logfile C:\orant\database\log3orcl.ora;
ALTER DATABASE drop logfile C:\orant\database\log4orcl.ora;

Initoral. Ora configuration:
sga=db_block_buffers*db_block_size+share_pool_size+log_buffers+sort_arer_size+1m
=1/3--1/2
Take 128M for example:

db_block_buffers=16000 (DB_BLOCK_SIZE=2K)
share_pool_size=30720000 (server to increase 10 times times)
log_buffers=655360
sort_area_size=327680 (server to increase 100 times times)----------add
Global_name=false
rollback_segements= (RB1,RB2)//General large database to establish 6-8 rollback segments

Add:
dml_locks=1000
open_cursors=200