Run it ;-)
Well, I think you should know something before you begin. 'Iptables' is a piece of code in Linux kernel. It is a system for network filtering, NAT, connection tracking etc. Your script probably just executes commands that set parameters for this system and maybe some other parts of Linux networking. So, if you run it, it will create several 'tables' or sets of rules for handling network connections. You can check them with commmand 'iptables -L -n'.
I think you will want to run it after reboot. In RedHat systems, the system is a little bit different. There is a 'service' called iptables found in /etc/init.d. When it is run, it just loads these tables from file. Check this file and decide if you want to replace it with your script. Just be careful if you are not sitting on system console - you can easily block remote acces for yourself.