"CES191" humidity sensor [solved]

is this right?

It would have been better if you Auto Formatted it and posted it in code tags like this

int sensor = 1;
unsigned long startMillis;  //some global variables available anywhere in the program
unsigned long currentMillis;
const unsigned long period = 1000;  //the value is a number of milliseconds
const byte ledPin = 13;    //using the built in LED
int lowstate = 0;
int hightstate = 0;
long ratio = 0;

void setup()
{
  Serial.begin(9600);
  pinMode(sensor, INPUT);
  startMillis = millis();  //initial start time
}

void loop()
{
  currentMillis = millis();
  int state = digitalRead(sensor);
  if (state == 1) hightstate = hightstate + 1;
  if (state == 0) lowstate = lowstate + 1;
  ratio = hightstate / (lowstate + hightstate);
  if (currentMillis - startMillis >= period)  //test whether the period has elapsed
  {
    Serial.println(state);
    startMillis = currentMillis;  //IMPORTANT to save the start time of the current LED state.
  }
}

The idea looks OK but

1 - you don't need to count both the HIGH and LOW states
2 - do any calculations at the end of the period
3 - you should really count when the input becomes HIGH rather than when it is HIGH
4 - why are you printing state ?