sambavan, Thank you very much for your help.
Finally I succesful install Oracle. but I still have 3 couple problems in the following:

1. In the installation the Create Database Assistance Step Fail. the error is Oracle Not Available.
2. startup nomount pfile=initorcl.ora is fail and get error
ORA-03113 end-of-file on communication channel.
but if I run as: startup nomount
it works fine. but when I issue ALTER DATABASE MOUNT,
I got error db_name is 'orcl' not the 'world'
3. If I change the db_name in the initorcl.ora from 'orcl' to 'world' then I can ALTER DATABASE MOUNT and ALTER DATABASE OPEN.
4. When I use the data base configuration assistance to create the database name 'World' the first name I got error "Oracle Not Available", then I have went to Startup the Instance first then run the dbassist it create the database name "world" for me.

Why if I do not specific the PFILE= it works. and why I need to change the db_name from 'orcl' to world.

Thank you very much for any comments.