how to do a serial communication using RS232 port in matlab??

My project is relating to the RFID technology.12 digit serial code is to be received through the RXD pin of RS232 port and displayed in a GUI.i have prepared the gui in matlab.

DOUBT1:how will i be able to display this 12 digit serial code in a box?(i have created this box in gui).code should be displayed as soon as it is received on the rs232 port

DOUBT2:i created a new file and saved it by name RFID.two such files were created by name RFID.fig and RFID.m.opening the files opens the GUI(actual) and code respectively,but not the GUI editor pallete where i have designed the GUI. Im new in using matlab.answer in simple understandable words.

Thankyou.