Ok, I have a question here...

I have an iPhone, and have set up the vnc client to the point where I can control my MBP from the iPhone on my home network. My question is how would I set up the iphone to allow me to control it from work whenever i want? I'm not all that familiar with ip addresses and such. All I know is that I'm going to have to allow for port forwarding of 5900 on my home router. Can anyone help me? Thanks in advance.