In setup(), start serial and choose your speed:

Serial.begin(9600);

Wherever you want to write to serial:

Serial.write("write this");

Wherever you want a newline:

Serial.println();

In setup(), start serial and choose your speed:

Serial.begin(9600);

Wherever you want to write to serial:

Serial.write("write this");

Wherever you want a newline:

Serial.println();

example

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  Serial.write("Hello World");

}

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

}