TSL 235R Light to Frequency Converter

Hi, I am a newcomer in the arduino field. I am interested in having a light sensor for the detection of light, particularly the detection of rapidly changing low light levels. In this respect, the TSL235R LtoFC seems to be a very good option for a sensor. Although it is possible to find many codes for doing light level measurements using TSL 235R, it is evident that the proper coding implies a deep understanding of the inner working of the arduino system (i.e. timers) and arduino syntax. I want and need to implement a system for light sensing using the TSL235R LtoFC for what I would appreciate if someone can explain in a general way (or indicate were to find such an explanation) the communication between the TSL235R sensor, signals and the arduino hardware and syntax. Best,

period = pulseIn(pin, 1)<<1; // microsecs