i just received a rfid reader with some tags,
Link?
Without further information it is hard to say what is going wrong.
Has the RFID reader got an RS232 output? If so are you converting it to TTL voltages before sending it into the arduino.
Have you got the TX & RX the right way round, depending on how the reader is designated you could have to connect TX to TX or TX to RX.
The code is a bit wrong as it will print every character on a new line but you should see something.