How to WRITE android data to Mysql using webservices (Asynctask)?

Question

I have an android application that has several buttons on different screens, I must join the buttons clicked and send to Mysql. I read about webservices (http://www.androidpro.com.br/webservice/) and you need an Asynctask to make that connection.

banco_mysql.java

package com.example.deadsec.gerflores_beta;



import android.os.AsyncTask;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;


/**
 * Created by DEDSEC on 24/04/2017.
 */

public class banco_mysql extends AsyncTask<Void, Void, String> {
    @Override
    public String doInBackground(Void... params) {

        HttpURLConnection urlConnection = null;
        BufferedReader reader = null;

        try {
            URL url = new URL("http://IP:PORTA/BANCO/USUARIO/SENHA");
            urlConnection = (HttpURLConnection) url.openConnection();
            urlConnection.setRequestMethod("GET");
            urlConnection.connect();

            InputStream inputStream = urlConnection.getInputStream();

            reader = new BufferedReader(new InputStreamReader(inputStream));

            String linha;
            StringBuffer buffer = new StringBuffer();
            while((linha = reader.readLine()) != null) {
                buffer.append(linha);
                buffer.append("\n");
            }

            return buffer.toString();
        } catch (Exception e) {
            e.printStackTrace();
            if (urlConnection != null) {
                urlConnection.disconnect();
            }

            if (reader != null) {
                try {
                    reader.close();
                } catch (IOException e1) {
                    e1.printStackTrace();
                }
            }
        }

        return null;
    }
    @Override
    protected void onPostExecute(String dados) {
        // Faça alguma coisa com os dados
    }
}

I don’t quite understand how you’re connecting with the bank, how to implement this in the Activity_final to gather the data (clicked buttons) and how to send to the bank.
please help me.