We’ll assume that you have a server running tightvnc server. If you dont, search this site for tutorials on the same.
Now, on the client PC, install xtightvncviewer to connect to the server:
sudo apt-get install xtightvncviewer
here, 126.96.36.199 is the ip of the server, and 5901 is the port (default tightvnc server port).