MIDI over USB with Arduino UNO (Solved)

hi dhunt,
i am working on a midi keyboard using arduino uno,thinking of how to add usb midi to it, am new to it,
only experience is midi music programing,some how wrote the code for midi keys (4) and uploaded into arduino
now wants to check it but no way to connect through usb...i amusing a mac mini os siera version 10.12.6
really need help.... i have checked your links but its not opening..
here is the program i wrote
#include <MIDI.h>

MIDI_CREATE_DEFAULT_INSTANCE () ;

void setup() {
// MIDI.bein (MIDI_CHANNEL_OMNI);

// pinmode(2, INPUT_PULLUP);
// pinmode(3, INPUT_PULLUP);
// pinmode(4, INPUT_PULLUP);
// pinmode(5, INPUT_PULLUP);

}

void loop() {
// int sensorval() - (
// !digitalread(2), !digitalread(3),
// !digitalread(4), !digitalread(5)

// for {int j - 0; j < 4; j++} {
// if (sensorval(j) ! - mem (j1) (
// mem (j) - sensorval (j);

// if mem (j1) (
// MIDI.sendNoteOn(j + 48, 64, 1);
// ) else (
// MIDI.sendNoteOff(j + 48, 64, 1);

};

thanks ajiesh