General :: Open Port In The Firewall?

I want to open port 2700 on my firewall but I don't know how I try with Code:iptables -A INPUT -i eth0 -p tcp --sport 2700 -m state --state ESTABLISHED -j ACCEPT But the port is not open I see the firewall configuration with the command setup . I use CentOS 5.3 here a screen of my configuration :http://upbg.net/out.php/i3537_sshot3.pngCurrently my firewall is off because I don't know how to turn on 2700 when the port is open I will turn on firewall .If I write 2700 in other ports field will 2700 be open ? Before 1 month I try but the port was not open . I have only 1 last question will firewall reduce the load of the my server now mysql use many CPU % and I just don't know why