New to Light Sensors

I am just starting out with arduino using a 32u4
I have some basic knowledge of JavaScript and c++, however I can't figure out how to make this thing work. Any suggestions on books or things I should do to become better are welcome.

Below is the beginning of my code. The purpose is to make the robot stop when it senses a light color(White).

This is the sensors
This is the pin layout
void setup() {
// put your setup code here, to run once:
pinMode(9,OUTPUT);//Left motor
pinMode(10,OUTPUT);//Right motor
pinMode(18,INPUT);//right line sensor
pinMode(21,INPUT);//left line sensor
}

void loop() {
// put your main code here, to run repeatedly:

if(analogRead(21) == false)//If the light sensor doesn't see white go forward
{
analogWrite(9,125);
analogWrite(10,125);
}else{
analogWrite(9,0);
analogWrite(10,0);
}
}

if(analogRead(21) == false)//If the light sensor doesn't see white go forward

"false" is defined to be 0. It is extremely unlikely that you will see an analog reading of 0.

Print out some values returned by analogRead(21), while pointing at various light sources, to help you choose a more sensible value.

I had totally misunderstood the part. I am trying to use analogRead(21) and serial.println however the only value returned is 0.00. Why is it doing this, and how do I fix it?

void setup() {
// put your setup code here, to run once:
Serial.begin(1200);
}

void loop() {
// put your main code here, to run repeatedly:
int sensorValue = analogRead(21);
float volt = sensorValue;
Serial.println(volt);

}

Why aren't you using the Pololu Zumo library functions for reading those sensors? It is likely that more than just analogRead() is involved.

I suggest that you spend some time with the Zumo 32U4 documentation and use the sensors as they were designed to be used.

I didn't even know that existed thanks for the help I guess it's time to start reading again.