Remote access to a dhcp pc from ooutside network

jody press jody "at"
Tue Apr 20 17:00:01 2004

I have a small home network which connects to the internet through a
wireless router with dhcp enabled. Within the network vnc works perfectly.
But how can I remotely connect to one of the pc's which has an internal ip
address. How do I find out my ip address from the isp, which is then routed?
Many thanks