How to use PWM ?

How to use PWM ?

i try analogWrite() not work

```
#include <Arduino.h>

/* PC1 as blinky LED, change here as needed */
#define LED PD2

void setup() {
    pinMode(LED, OUTPUT);
    analogWriteFrequency(20000);
}

void loop() {
//    digitalWrite(LED, HIGH);
//    delay(500);
//    digitalWrite(LED, LOW);
//    delay(500);

    analogWrite(LED, 100);
}
```


