<Window x:Class="ProjectBilling.MVVM.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="Главное окно" Height="350" Width="525">
    <Grid Name="grid1">
        <Grid.RowDefinitions>
            <!-- Две строки -->
            <RowDefinition></RowDefinition>
            <RowDefinition></RowDefinition>
        </Grid.RowDefinitions>
        <TextBox x:Name="textBox1" 
                 Height="40" 
                 TextWrapping="Wrap" 
                 Text="Текст сообщения"  
                 Grid.Row="0"/>
        <Button Name="showButton" 
                Content="Текст кнопки"  
                    Margin="5"
                Click="ShowButton_Click" 
                Grid.Row="1" />
    </Grid>
</Window>

// Add the second text cell to the Grid
TextBlock txt2 = new TextBlock();
txt2.Text = "Quarter 1";
txt2.FontSize = 12;
txt2.FontWeight = FontWeights.Bold;
Grid.SetRow(txt2, 1);
Grid.SetColumn(txt2, 0);