Creating a Calculator Android app

I'm learning android programing and i just dont know how turn my xml into a working calculator.

here is my xml, i removed the styling for better reading

<RelativeLayout xmlns:android="http://ift.tt/nIICcg"
xmlns:tools="http://ift.tt/LrGmb4"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.afm.calculator.MainActivity" >

<TextView
    android:id="@+id/tvresult"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text=""
    android:textSize="40dp" />

<Button
    android:id="@+id/times"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="x"
    android:textSize="40sp" />

<Button
    android:id="@+id/plus"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="+"
    android:textSize="40dp" />

<Button
    android:id="@+id/divide"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="÷"
    android:textSize="40sp" />

<Button
    android:id="@+id/mines"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="-"
    android:textSize="40sp" />

<Button
    android:id="@+id/equal"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="="
    android:textSize="40sp" />

<EditText
    android:id="@+id/editText1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:ems="10"
    android:inputType="numberDecimal" >

</EditText>

<EditText
    android:id="@+id/editText2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:ems="10"
    android:inputType="numberDecimal" />

</RelativeLayout>

here is my java:

package com.afm.cal;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends Activity implements android.view.View.OnClickListener {

Button mines, plus, divide, times, equal;
EditText eto, ett;
TextView tv;

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

    mines = (Button) findViewById(R.id.mines);
    plus = (Button) findViewById(R.id.plus);
    divide = (Button) findViewById(R.id.divide);
    times = (Button) findViewById(R.id.times);
    equal = (Button) findViewById(R.id.equal);
    eto = (EditText) findViewById(R.id.editText1);
    ett = (EditText) findViewById(R.id.editText2);
    tv = (TextView) findViewById(R.id.tvresult);



}


public void onClick(View arg0) {

}

}

please help me finish it and thx in advance