Mediaplayer in service for Radio Streaming app

I made an app for an online radio in a town, I would like to know if you can help me to play in the background in a service, so that I tell you to kill the main activity, the radio keeps listening.

I share code with you:

package ar.com.asset.www.radiostream;

import android.media.AudioManager;
import android.media.MediaPlayer;
import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

import java.io.IOException;

public class MainActivity extends AppCompatActivity {

Button btnplay;
Button btnstop;
MediaPlayer mediaPlayer;

boolean prepared = false;
boolean started = false;

String stream = "http://radioscoop.hu:80/live.mp3";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    btnplay = (Button) findViewById(R.id.btnplay);
    btnstop = (Button) findViewById(R.id.btnstop);
    btnplay.setEnabled(false);
    btnplay.setText("CARGANDO");
    mediaPlayer = new MediaPlayer();
    mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);

    new PlayerTask().execute(stream);

    btnplay.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if (started) {
                started = false;
                mediaPlayer.pause();
                btnplay.setText("Play");
            } else {
                started = true;
                prepared = true;
                mediaPlayer.start();
                btnplay.setText("Pause");
            }
        }
    });

    btnstop.setOnClickListener(new View.OnClickListener() {

        @Override

        public void onClick(View v) {
            started = false;
            mediaPlayer.stop();
            btnplay.setText("Play");

            try {
                mediaPlayer.prepare();
                prepared = true;
            } catch (IOException e) {
                e.printStackTrace();
            }

        }


    });
}


class PlayerTask extends AsyncTask<String, Void, Boolean> {
    @Override
    protected Boolean doInBackground(String... strings) {
        try {
            mediaPlayer.setDataSource(strings[0]);
            mediaPlayer.prepare();
            prepared = true;
        } catch (IOException e) {
            e.printStackTrace();
        }
        return prepared;
    }

    @Override
    protected void onPostExecute(Boolean aBoolean) {
        super.onPostExecute(aBoolean);
        btnplay.setEnabled(true);
        btnplay.setText("PLAY");
    }

}

@Override
protected void onPause() {
    super.onPause();

}

@Override
protected void onResume() {
    super.onResume();

}

@Override
protected void onDestroy() {
    super.onDestroy();

}

}