Reading encoder data using RS232

I am using an US Digital E4P optical encoder which has 4 output pins: 1) +5V 2) A Channel 3) Ground 4) B Channel

I have a 9 pin serial port(RS232) and a 25 pin port in my computer and I want to read the encoder data (angular position) into MATLAB. Please help me to understand, to which pins of the serial port should I connect the 4 pins of the encoder and how can I read the signal to get angular position data in MATLAB?