Need help connecting via Internet

[Ian McDowell]

I may be missing something very simple here as I'm kinda a noob to VNC 
but I am trying to connect to one of my home pcs via the internet from 
my Pc in work, however I have a router at home.  Now I know what my 
external IP address is for the router and I know what my internal IP is 
for the PC I'm trying to connect to, however I don't know how to get 
the viewer on my work pc to connect with my home pc.  Is there a simple 
way of telling the viewer to first connect to the external IP then to 
the Internal IP or am I missing something Can anyone please help?

I have VNC working between my 2 networked PCs really easily using the 
internal IP addresses, I just don't know how to connect from an 
external PC.

Thanks

Ian