Hi there,
About change serial port you can change the code.
As you see the WIKI told you there are 4 of pins which are unused D0,D1,A4,A5.
#include <SoftwareSerial.h> //Software Serial Port
#define RxD 6
#define TxD 7
This is from example code. You need to change to A4,A5 port.
Like:
#include <SoftwareSerial.h> //Software Serial Port
#define RxD 18
#define TxD 19
And then you just need to use jumper wire to connect pin A5, A4 to RX, TX that should be work.
Best regards,
Yuri