On the client side the users will need to fill in the IP address or domain of the server. If that IP is on the Internet or somewhere else that will work as long as the client PC has physical access and permission to open a tcp connection (no firewalls that block the port you are using etc.)
Make a connect dialog that pops up if the user chooses to connect and have the user input the IP there and click OK. You can add functionality like bookmarks and "home page" to make things easier. If a home page / server is defined the client can connect to that upon startup. You may want also to add functionality that will reconnect in the background if the connection is lost. The client's IP is of less interest. If you need it though just use the string to IP function and the IP to string function from the tcp/ip palette. Do not wire anything to the former funtion but wire it's output to the latter. The latter will then output the IP of the local PC.
