how to make a chatting program in vb.net win form

Hey there !

I think this can be done with the help of remote procedure call, there are several tutorials for that, I am sharing you some of the links for chat server from which you can take help :

1) https://www.codeproject.com/Articles/38914/A-TCP-IP-Chat-Program

2) http://www.instructables.com/id/How-to-make-a-simple-chat-program-in-visual-basic-/

3) https://www.experts-exchange.com/articles/11178/A-Peer-To-Peer-LAN-Chat-Application-in-Visual-Basic-Net-using-TcpClient-and-TcpListener.html

4) https://code.msdn.microsoft.com/windowsdesktop/Simple-Chat-Application-3f7f4ec5

Hope that helps