BTserial Use in Arduino

Hello, I was wondering if anyone knew where I could find the bluetooth serial library for the BTserial command in Arduino IDE? **** Update I am new and made a simple mistake that I had just found. It's corrected. Thank you!*****

We need SoftwareSerial.h Library which is automatically included in the relevant folder of the PC during installation phase of the IDE. We just make the following declarations in the global space of the sketch.

#include<softwareSerial.h>
SoftwareSerial BTserial;