After compiling, there will be two executables: server and client
Run the server by doing:
./server [Port]
or just
./server

The default port is 9999


Run the client by doing:
./client [Username] [Host] [Port]


The client is mostly the same except for the existence of a static 
global variable (sorry). The client's socket fd to the server is global
so the client's interrupt handler can send a message to the server telling 
it that the client has disconnected.