To run the application, you must have jdk-7 installed(and path for java must be set in operating system).
Migrate to the master directory containing Server.java & Client.java files.
Open the terminal and type the following commands:
javac Server.java - to compile the Server.java file.
javac Client.java - to compile the Client.java file.
java Server - to run the server.
java Client - to run the client.
Now the client and the server can communicate.