Blinking and Dimming Several LEDs at the Same Time

if these 3 steps are true, just combine what's given

the hints grumpy gave already.

and then you might come up with something like

const int adcPin = A1;
//const int led [] = {23, 22, 21, 20, 19, 18, 17, 16, 15, 14};
const int led [] = {3, 5, 6, 9, 10, 11, 3, 5, 6, 9};  // on UNO only  3, 5, 6, 9, 10 und 11.
const byte numberOfLeds = 10;
byte ledState = LOW;             // ledState used to set the LED
unsigned long previousMillis = 0;        // will store last time LED was updated
const long interval = 1000;           // interval at which to blink (milliseconds)
const int adcResolution = 1024;
const int pwmResolution = 256;

void setup()
{
  Serial.begin(115200);
  Serial.println(F("Blink Without Delay PWM LEDs"));
  for (byte i; i < numberOfLeds; i++) {
    pinMode(led[i], OUTPUT);
  }
  pinMode(adcPin, INPUT);
}

void loop()
{
  //read a potentionemter
  int adc = analogRead(adcPin);
  //Blink a LED (or many LEDs) between dark and the calculated PWM value
  unsigned long currentMillis = millis();
  if (currentMillis - previousMillis >= interval) {
    // save the last time you blinked the LED
    previousMillis = currentMillis;
    // if the LED is off turn it on and vice-versa:
    int pwmToSet = 0;
    if (ledState == LOW) {
      ledState = HIGH;
      //set a PWM Value to the given ADC Read out
      pwmToSet = map(adc, 0, adcResolution - 1, 0, pwmResolution - 1);
      Serial.print(F("adc=")); Serial.print(adc);
      Serial.print(F("   pwmToSet=")); Serial.println(pwmToSet);
    } else {
      ledState = LOW;
      Serial.println(F("all LEDs off"));
    }
    // set the LED with the ledState of the variable:

    for (byte i = 0; i < numberOfLeds; i++) {
      //digitalWrite(led[i], ledState);  // no we don't want to write on, off any more
      analogWrite(led[i], pwmToSet);
    }
  }
}

This code is non optimized in any way, to keep it as consistent with the existing examples as possible.

If you don't understand a line - asking is still allowed after you have checked the examples and Google.

You will even find the 3 lines of "feature requests" as comments in the code. This is to show you how to elaborate a "program". Define what's wanted, bring it in an order and finally code it. If you are not good in coding - try to reuse as many examples as possible. The IDE comes with tons of examples for you.