WeACT Black Pill SMT32F411 Boot Loader

Hello,

Anyone know where to find and how to install the boatloader for WeAct SMT32F411 Black Pill boards please.
I am using an STLink to program the board but the serial monitor does not work?
The LED in the app below blinks but no serial output.
Many thanks imk

#define LED_PIN PC13
void setup()
{
Serial.begin(9600);
delay(1000);

pinMode(LED_PIN, OUTPUT);
}

void loop()
{
Serial.println("Initialize Sensor OK");

digitalWrite(LED_PIN, HIGH);
delay(100);
digitalWrite(LED_PIN, LOW);
delay(100);
}