As Dave said, you cannot do this. You would have to install a client version of your software that is listening on a certain port. Then you can have a server version of your software that sends messages on that port. However, if you do not need to ask for input and all machines are Win7 or higher, you can use msg. Open a command line and type msg and you'll see the options, http://pcsupport.about.com/od/commandlinereference/p/msg-command.htm[^].
There are only 10 types of people in the world, those who understand binary and those who don't.