i'm doing this usb device project at my uni. I want to make alarm(buzzer) and Lamp(led) to work from infrared sensor output via usb.When ir sensor detect motion it will make the alarm&lamp on. Then also sending mail. Im using pic 18f2550-1/sp(usb Fsio from km2.net).But i dont know how to start the program. Can somebody help me?

computer--->port 1(for analog input)--->infrared sensor--->port2(digital output)--->computer
then from the output,
computer----> port 1&2 ----> (alarm & lamp work)