How set my.cnf

Hi everybody,

I tried many times to set my file my.cnf to get a fast mysql command

When i have all user work on my website, mysql command go to 280% usage CPU, so i check my tuning-primer to know what i must change for completed usage

So i should change my my.cnf but i don't know what change on this file

for now my file is like that:
--------------------------------------------------------------------------------------------
[mysqld]
bind-address=127.0.0.1
local-infile=0
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
user=mysql

# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0

[mysqld_safe]
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid

set-variable=max_connections=250
--------------------------------------------------------------------------------------------

So, i came to you to beg for knowing the good setting to use

My serveur run with


CPU GenuineIntel, Intel(R) Xeon(R) CPU E31220 @ 3.10GHz
Version Parallels Plesk Panel v11.0.9_build110120608.16 os_CentOS 6
OS CentOS 6.3 (Final)

Thx very much for your help