How to receive data from setpu{} to computer through bluetooth ?

Projects Networking, Protocols, and Devices
3

I want to send a char to active the dc motors car moving foward by bluethooth.
So I need to check whether the bluetooth is connected , it should print "Send any character to begin" and wait a char to be send if it is connected successfully.
then I push a button to send any char to the arduino to make the car moving forward ,like this :

 void setup() {
 Serial.begin(9600);
 pinMode(InA1, OUTPUT);
 pinMode(InB1, OUTPUT);
 pinMode(PWM1, OUTPUT);
 
 pinMode(InA2, OUTPUT);
 pinMode(InB2, OUTPUT);
 pinMode(PWM2, OUTPUT);
 


    
    Serial.println("\nSend any character to begin : ");
    while (Serial.available() && Serial.read()); // empty buffer
    while (!Serial.available());                // wait for data
    while (Serial.available() && Serial.read()); // empty buffer again
  
}
void loop() {
 analogWrite(PWM1,100);
 analogWrite(PWM2,100); 
 digitalWrite(InA1, LOW);
 digitalWrite(InB1, HIGH);
 digitalWrite(InA2, LOW);
 digitalWrite(InB2, HIGH);}

The arduino can wait the char and active by sending a char ,but it doesn't show the string "\nSend any character to begin : ".