I'm at home on a snow day with no access to my computer at work. My computer is, naturally, on a network and it's address is 192.168.xxx.xxx (I think we're on a T1). If I run VNC on that computer ...

Note that <ip_address> is the IP address of the computer. Note that it is not necessary to know an IP address in order to find other systems if you have a WiFi LAN connection.