Part 1 Complete code (Windows Store apps using C#/VB and XAML)

<Application
    x:Class="HelloWorld.App"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:HelloWorld"
    RequestedTheme="Light">

    <Application.Resources>
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <!-- 
                    Styles that define common aspects of the platform look and feel
                    Required by Visual Studio project and item templates
                 -->
                <ResourceDictionary Source="Common/StandardStyles.xaml"/>
            </ResourceDictionary.MergedDictionaries>
            <Style x:Key="BigGreenTextStyle" TargetType="TextBlock">
                <Setter Property="Foreground" Value="Green"/>
                <Setter Property="FontSize" Value="36"/>
                <Setter Property="FontFamily" Value="{StaticResource ContentControlThemeFontFamily}"/>
                <Setter Property="TextTrimming" Value="WordEllipsis"/>
                <Setter Property="TextWrapping" Value="Wrap"/>
                <Setter Property="Typography.StylisticSet20" Value="True"/>
                <Setter Property="Typography.DiscretionaryLigatures" Value="True"/>
                <Setter Property="Typography.CaseSensitiveForms" Value="True"/>
            </Style>

        </ResourceDictionary>
    </Application.Resources>
</Application>

<common:LayoutAwarePage
    x:Name="pageRoot"
    x:Class="HelloWorld.MainPage"
    DataContext="{Binding DefaultViewModel, RelativeSource={RelativeSource Self}}"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:HelloWorld"
    xmlns:common="using:HelloWorld.Common"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">

    <Page.Resources>
        <!-- TODO: Delete this line if the key AppName is declared in App.xaml -->
        <x:String x:Key="AppName">Hello, world!</x:String>
    </Page.Resources>

    <!--
        This grid acts as a root panel for the page that defines two rows:
        * Row 0 contains the back button and page title
        * Row 1 contains the rest of the page layout
    -->
    <Grid Style="{StaticResource LayoutRootStyle}">
        <Grid.RowDefinitions>
            <RowDefinition Height="140"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>

        <!-- Back button and page title -->
        <Grid>
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="Auto"/>
                <ColumnDefinition Width="*"/>
            </Grid.ColumnDefinitions>
            <Button x:Name="backButton" Click="GoBack" 
                    IsEnabled="{Binding Frame.CanGoBack, ElementName=pageRoot}" 
                    Style="{StaticResource BackButtonStyle}"/>
            <TextBlock x:Name="pageTitle" Grid.Column="1" 
                       Text="{StaticResource AppName}" 
                       Style="{StaticResource PageHeaderTextStyle}"/>
        </Grid>
        
        <!-- Controls added in PART 1. -->
        <StackPanel Grid.Row="1" Margin="120,30,0,0">
            <TextBlock Text="What's your name?" Style="{StaticResource BasicTextStyle}"/>
            <StackPanel Orientation="Horizontal" Margin="0,20,0,20">
                <TextBox x:Name="nameInput" Width="300" HorizontalAlignment="Left"/>
                <Button Content="Say &quot;Hello&quot;" Click="Button_Click"/>
            </StackPanel>
            <TextBlock x:Name="greetingOutput" Style="{StaticResource BigGreenTextStyle}"/>
        </StackPanel>
        <!-- End -->

        <VisualStateManager.VisualStateGroups>

            <!-- Visual states reflect the application's view state -->
            <VisualStateGroup x:Name="ApplicationViewStates">
                <VisualState x:Name="FullScreenLandscape"/>
                <VisualState x:Name="Filled"/>

                <!-- The entire page respects the narrower 100-pixel margin convention for portrait -->
                <VisualState x:Name="FullScreenPortrait">
                    <Storyboard>
                        <ObjectAnimationUsingKeyFrames Storyboard.TargetName="backButton" 
                                                       Storyboard.TargetProperty="Style">
                            <DiscreteObjectKeyFrame KeyTime="0" 
                                                    Value="{StaticResource PortraitBackButtonStyle}"/>
                        </ObjectAnimationUsingKeyFrames>
                    </Storyboard>
                </VisualState>

                <!-- The back button and title have different styles when snapped -->
                <VisualState x:Name="Snapped">
                    <Storyboard>
                        <ObjectAnimationUsingKeyFrames Storyboard.TargetName="backButton" 
                                                       Storyboard.TargetProperty="Style">
                            <DiscreteObjectKeyFrame KeyTime="0" 
                                                    Value="{StaticResource SnappedBackButtonStyle}"/>
                        </ObjectAnimationUsingKeyFrames>
                        <ObjectAnimationUsingKeyFrames Storyboard.TargetName="pageTitle" 
                                                       Storyboard.TargetProperty="Style">
                            <DiscreteObjectKeyFrame KeyTime="0" 
                                                    Value="{StaticResource SnappedPageHeaderTextStyle}"/>
                        </ObjectAnimationUsingKeyFrames>
                    </Storyboard>
                </VisualState>
            </VisualStateGroup>
        </VisualStateManager.VisualStateGroups>
    </Grid>
</common:LayoutAwarePage>

using System;
using System.Collections.Generic;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;

// The Basic Page item template is documented at http://go.microsoft.com/fwlink/?LinkId=234237

namespace HelloWorld
{
    /// <summary>
    /// A basic page that provides characteristics common to most applications.
    /// </summary>
    public sealed partial class MainPage : HelloWorld.Common.LayoutAwarePage
    {
        public MainPage()
        {
            this.InitializeComponent();
        }

        /// <summary>
        /// Populates the page with content passed during navigation.  Any saved state is also
        /// provided when recreating a page from a prior session.
        /// </summary>
        /// <param name="navigationParameter">The parameter value passed to
        /// <see cref="Frame.Navigate(Type, Object)"/> when this page was initially requested.
        /// </param>
        /// <param name="pageState">A dictionary of state preserved by this page during an earlier
        /// session.  This will be null the first time a page is visited.</param>
        protected override void LoadState(Object navigationParameter, Dictionary<String, Object> pageState)
        {
        }

        /// <summary>
        /// Preserves state associated with this page in case the application is suspended or the
        /// page is discarded from the navigation cache.  Values must conform to the serialization
        /// requirements of <see cref="SuspensionManager.SessionState"/>.
        /// </summary>
        /// <param name="pageState">An empty dictionary to be populated with serializable state.</param>
        protected override void SaveState(Dictionary<String, Object> pageState)
        {
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            greetingOutput.Text = "Hello, " + nameInput.Text + "!";
        }
    }
}