1. First try accessing the application on the target PC, using only your local network. So get a 2nd PC on your network to test with. The application running on your PC will need to be accessed via an IP address and port number. Eg. 192.168.0.2:7890. You will need to unblock this port (7890 in my example) in the Windows Firewall settings, else the connection will be rejected. Check your application settings to see which port it is accepting requests on. Only proceed to the next step if you can get it working on your local network, from a 2nd PC.
2. Next, you need to enable remote management on your router, and try to access your router web interface from the internet, from a PC not connected to your local network (else NAT loopback will screw you). Try a 3G connection from your phone tethered to your PC, or simply use the web browser built into your phone. Type in the public IP address of your ADSL connection (get it from your router web interface, or even your ADSL provider's client zone login) into the web browser, and don't forget the specific port number for remote management if you have enabled this option: e.g.
http://196.123.123.123:8080.
3. Once you have that working, then start with the port forwarding. You will want to set up a port forward from a public facing port on your router, to a local IP address and port combo. E.g. 196.123.123.123:456 --> 192.168.0.2:7890. You have to make use of 2 port numbers, one on either side of the connection, unless you set your PC as a DMZ, in which case all incoming traffic from the outside will be forwarded to your PC (not recommended, unless you have a good firewall setup, and you know what you are doing, which I don't think you do, no offense).
4. Lastly, when you have all that working, you'll want to set up a DynDNS account for your router, so you don't have to remember IP addresses, or continuously check for your latest public IP address of your ADSL connection (it changes every 24 hours or so). Head on over to
http://www.dyndns.com, and register for a free account. You will be able to register your own free domain name. eg: lourens.dyndnds.info. Then you can access your application on your PC via the hostname and not the IP address, e.g.
http://lourens.dyndns.info:456. You will need to configure your Netgear router with your DynDNS username and password, in order to allow your router to tell the DynDNS service what it's latest IP address is, so that DynDNS can associate it with your hostname.
Hope this helps. If not, tell us where you get stuck, and we'll try to assist.
