Hello. Im designing different electronics devices, mostly based on avr, arm MCUs and boards with them like arduino, stm-discovery etc. I can help you with your deal and since im new one here I can do it cheaper then anybody.
(autopromotion ^))
In general your project is check photoresistor, if light - rotate servo for some angle or number of circles.
BUT:
1 - what photoresistor and scheme? What voltage is "light" and "dark"?
2 - what servo and what angle to rotate for opening?
3 - how will all this be closed?
And many other questions.
So you have or provide all info for coder, or ask for designing full scheme and logic, providing full technical task.