How to Block website in RHEL 6 using squid proxy server

i m using squid proxy server....
now i want to block some websites using squid.conf file..
in this case, i write some entery for blocking..

acl mynet src 192.168.10.0/24
http_access allow mynet
http_port 3128

Now, In window Pc,IP:192.168.10.2/255.255.255.0/DG:192.168.10.1,and Tools,Internetoptions,connetion,lan seting , address:192.168.17.5 port:3128
now internet is working fine...

after that, i want to block some websites:
I make some entry:
#vim /etc/squid/block_list.txt
www.gmail.com
www.sex.com
www.orkut.com
:wq!
#vim /etc/squid/squid.com
acl block_list url_regex -i "/etc/squid/block_list.txt"
http_access deny block_list
:wq
#service squid restart
#chkconfig squid on

now i access any website at window clint pc..
like www.sex.com
this web site is open.....

so plz guide me , how to block webseits at