the sensor will probably work just like an ordinary potientiometer and that means that u will connect the power to the power connection on arduino and the ground to the ground on the arduino. the white cable u will connect to a analog pin.
then u use this code
int ledPin = 13;
int lightPin = 0;
int val = 0;
int value1 = 575;
void setup() {
pinMode(ledPin, OUTPUT);
beginSerial(9600);
}
void loop() {
val = analogRead(lightPin);
printInteger(val);
printByte(10);
printByte(13);
if(val<value1){
digitalWrite(ledPin, HIGH);
}
else ( digitalWrite(ledPin, LOW));
delay(200);
}
that code will get the value from the lightsensor and send it over serial to the computer (I guess it works the same with usb but since I have only worked with the serial version of arduino Im not sure) and if the value is under the value u state in the integer value1 (default to 575 this may need tweaking to match your sensor) the led at pin 13 will light up
then u can also read the value 0-1024 in a program like terminal which u can find here at the site to.
I hope this will help u.