Petzold code problem

I'm trying to run the following code (pages 32-33 of Petzolds Programming Windows 6th Edition)

using MSVS2012 Pro on Windows 8 Pro 64-bit.

(first excerpt from MainPage.xaml

            Background="{StaticResource ApplicationPageBackgroundThemeBrush}">
                            Text="Hello, Windows 8!"
                    FontSize="96"
                    FontWeight="Bold"
                    HorizontalAlignment="Center"
                    VerticalAlignment="Center" />
   

(second excerpt from MainPage.xaml.cs)

public MainPage()
        {
            this.InitializeComponent();
 
            // Create the foreground brush for the TextBlock
            LinearGradientBrush foregroundBrush = new LinearGradientBrush();
            foregroundBrush.StartPoint = new Point(0, 0);
            foregroundBrush.EndPoint = new Point(1, 0);
            GradientStop gradientStop = new GradientStop();
            gradientStop.Offset = 0;
            gradientStop.Color = Colors.Blue;
            foregroundBrush.GradientStops.Add(gradientStop);
            gradientStop = new GradientStop();
            gradientStop.Offset = 1;
            gradientStop.Color = Colors.Red;
            foregroundBrush.GradientStops.Add(gradientStop);
            txtblk.Foreground = foregroundBrush;
            // Create the background brush for the Grid
            LinearGradientBrush backgroundBrush = new LinearGradientBrush
            {
                StartPoint = new Point(0, 0),
                EndPoint = new Point(1, 0)
            };
            backgroundBrush.GradientStops.Add(new GradientStop
            {
                Offset = 0,
                Color = Colors.Red
            });
            backgroundBrush.GradientStops.Add(new GradientStop
            {
                Offset = 1,
                Color = Colors.Blue
            });
            contentGrid.Background = backgroundBrush;
        }

I get the following errors:

Error    1    The name 'Colors' does not exist in the current context    C:\TestProjects\Petzold

\GradientBrushCode\GradientBrushCode\MainPage.xaml.cs    34    34    GradientBrushCode
Error    2    The name 'Colors' does not exist in the current context    C:\TestProjects\Petzold

\GradientBrushCode\GradientBrushCode\MainPage.xaml.cs    38    34    GradientBrushCode
Error    3    The name 'Colors' does not exist in the current context    C:\TestProjects\Petzold

\GradientBrushCode\GradientBrushCode\MainPage.xaml.cs    50    25    GradientBrushCode
Error    4    The name 'Colors' does not exist in the current context    C:\TestProjects\Petzold

\GradientBrushCode\GradientBrushCode\MainPage.xaml.cs    55    25    GradientBrushCode

I searched and found similar posts that suggest adding:

using System.Drawing

I tried that but got another compiler error:

Error    1    The type or namespace name 'Drawing' does not exist in the namespace 'System' (are

you missing an assembly reference?)    C:\TestProjects\Petzold\GradientBrushCode\GradientBrushCode

\MainPage.xaml.cs    2    14    GradientBrushCode

I have no idea what to do.

Please help.

David