Dear ECCMOT,
I think you mixed different different types of data as alexxx said..First of all, rs232 connection needs a info exchanging protocol which is between two microprocessors. One is your pc and other can be a microcontroller or any gsm module.. I think in your project you must need a microcontroller.. You have to program it to detect signals from led and relay and then implement rs232 protocol in it also with program... according to the sensing the microcontroller will then send data through rs232 to trigger the software..
Do you work with MCUs?? You have to learn both programming and implementation of hardware. For now you can use transistors to amplify signals from led and send it to MCU by configuring one of it's port as input... Finally you have to make a clear statement about what you actually want to do?
Best of luck..
Rocket Scientist