You already used the sensor's data to calculate your heart's beats per minute (BPM). We can add to that code to get it to put the output on the OLED instead of the Serial Monitor. Here is a link to that Arduino file. Open this file on your computer and compile it.
If your sensor is powered correctly, you should see a little red light on it. If you do, put your thumb over the sensor and keep it there. After several seconds, it should level out your BMP reading.