Open firewall port on a Fedora machine on Amazon EC2

Hello, I have an application running on a Fedora 14 machine on Amazon EC2 small instance. The application takes an http request on a specific port and executes an action. This can simply be accomplished through Firefox for example when I call Firefox on the machine in putty and it renders locally through Xming. I want to accomplish the same when: - I call the machine using its public DNS through my local browser. - Also, when I make the http request from another instance on Amazon on the same security group. I did try to open this port both on the iptables of the machine and on the Amazon security group but I had no luck. Please note: In order to help me you will need to have Skype, teamviewer and a descent Internet connection. If you are experienced it should not take you more than 10 minutes. I have a Windows Vista machine with all the necessary tools such as putty, elasticfox etc... I can be online on the following hours as far as you let me know 1 day in advance: 5pm - 9pm GMT Monday to Friday and 2pm - 9pm GMT on weekends. Regards