Also the commands you give netcat means the following:

nc.exe (The Application itself)
-L (Constantly listen on a specified port)
-p (The port)
-d (Means that it if the command promp window is closed netcat will still be running)
-e (The exe you want to execute once a connection has been made to the port that you specified)

Hope it helps, thats just one of the many wonders you can do with netcat...