Network Address Translation techniques

[webmaster@goodwillinc.com]

I've been learning about vnc here on a network. I'd like to learn how to run the program to access a computer behind a firewall from an external location.   
   I'd like to use the program on a WAN.  Because each location will have several computers and a router, i'd like to install the program on each computer at each location.
   "dynamic IP address,www.dyndns.org/" --I'm going to look over this as well. Are there other places you can get similar programs?
 
With this program you would have to use the services of dyndns or like program if you were dealing with dynamic ip?.  I mean you couldn't just simply type in
the ip number:the ip networked computer:port right?
you couldn't say 64.85.4.34:192.168.0.xx:5580  
Thanks for all the help.
smitty