Windows Iot Core App for Raspberry Pi 2

MainPage.xaml

<Page
    x:Class="_1st_App.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:_1st_App"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">

    <Grid Background="White">
        <Button x:Name="button" Content="Add Those NUmber" HorizontalAlignment="Left" Margin="117,478,0,0" VerticalAlignment="Top" Height="41" Width="162" 
                Click="button_Click"/>
        <TextBlock x:Name="textBlock" HorizontalAlignment="Left" Margin="48,35,0,0" TextWrapping="Wrap" Text="Raspberry PI 2" 
                   VerticalAlignment="Top" Height="85" Width="499" FontSize="48"/>
        <Image x:Name="image" HorizontalAlignment="Left" Height="167" Margin="10,161,0,0" VerticalAlignment="Top" Width="1004" 
               Source="Assets/iot-hero-1920x320_LTR-languages_InvariantCulture_Default.jpg"/>
        <TextBlock x:Name="TB1" HorizontalAlignment="Left" Margin="117,567,0,0" TextWrapping="Wrap" Text="After Adding Those NUmber" 
                   VerticalAlignment="Top" Height="55" Width="479" SelectionHighlightColor="#FF3988C7" FontSize="29.333">
            <TextBlock.Foreground>
                <LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
                    <GradientStop Color="Black" Offset="0"/>
                    <GradientStop Color="#FF512828" Offset="1"/>
                </LinearGradientBrush>
            </TextBlock.Foreground>
        </TextBlock>
        <TextBox x:Name="tBox" HorizontalAlignment="Left" Margin="117,401,0,0" TextWrapping="Wrap" Text="" VerticalAlignment="Top" Height="27" Width="162"/>
        <TextBox x:Name="tBox2" HorizontalAlignment="Left" Margin="331,401,0,0" TextWrapping="Wrap" Text="" VerticalAlignment="Top" Height="32" Width="162"/>

    </Grid>
</Page>

MainPage.xaml.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices.WindowsRuntime;
using Windows.Foundation;
using Windows.Foundation.Collections;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Data;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Navigation;



namespace _1st_App
{
    
    public sealed partial class MainPage : Page
    {
        public MainPage()
        {
            this.InitializeComponent();
        }


        private void button_Click(object sender, RoutedEventArgs e)
        {
            int vl1 = Int32.Parse(tBox.Text);
            int vl2 = Int32.Parse(tBox2.Text);
            var Value = vl1 + vl2 ;
            TB1.Text = Value.ToString();
        }
    }
}