thanks PAVB
i did what you asked to do
but i don't know how to setup tnsnames.ora and listener.ora

bash-3.2$ cd /opt/oracle/
bash-3.2$ cd 10g/bin/
bash-3.2$ sqlplus /nolog

SQL*Plus: Release 10.2.0.1.0 - Production on Wed Oct 10 17:53:51 2007

Copyright (c) 1982, 2005, Oracle. All rights reserved.

SQL> conn sys as sysdba
Enter password:
Connected to an idle instance.
SQL> startup
ORACLE instance started.

Total System Global Area 2550136832 bytes
Fixed Size 1995856 bytes
Variable Size 587205552 bytes
Database Buffers 1946157056 bytes
Redo Buffers 14778368 bytes
Database mounted.
Database opened.
SQL> exit

bash-3.2$ ps -ef | grep smon
root 1611 1 0 11:34:23 ? 0:00 /etc/opt/resmon/lbin/emsagent
root 1540 968 0 11:34:19 ? 0:00 /etc/opt/resmon/lbin/registrar
root 1880 1 0 11:34:34 ? 0:00 /etc/opt/resmon/lbin/p_client
oracle 3434 1 0 17:55:14 ? 0:01 ora_smon_TC