How to use ARD 2.2 to connect to another computer on the internet

My uncle and I live in different cities and we each have Apple Remote Desktop 2.2 installed. We want to try and connect to each others computers and control it.

I was successful in controlling another computer on my WiFi network in my own house, but we couldn't figure out how to connect to his computer. Yes, he's set up his computer to allow Apple Remote Desktop in System Preferences > Sharing, so that's not the problem.

I don't know what I must enter to find his computer on the network. Do I use his IP address and/or his Router's IP address? I read somewhere in this forum that I might have to access a certain port on his router.

Does anybody have experience connecting to another mac with ARD over the internet?

Yeah you'll need to open up the ARD port(s) on his router for you to access him. I believe the ports are 3283 and 5900. If you have the Airport Base Station you would go into the Airport Admin Utility and then configure your IP address, go to Port Mapping, then map your public ports above to your private IP and to the same Private port as your public port. This will allow you in.