AddPostPage.xaml

<Page
    x:Class="CollectAnswers.AddPostPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:CollectAnswers"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">

    <Grid>
        <Button Style="{StaticResource NavigationBackButtonNormalStyle}" VerticalAlignment="Top" Margin="16" Click="Button_HandleBack"/>
        <Grid VerticalAlignment="Center" Background="White"
              Margin="16"
              Padding="32">
            <Grid.RowDefinitions>
                <RowDefinition Height="auto"/>
                <RowDefinition Height="auto"/>
                <RowDefinition Height="auto"/>
                <RowDefinition Height="auto"/>
                <RowDefinition Height="auto"/>
            </Grid.RowDefinitions>
            <TextBlock Grid.Row="0"
                       Text="Collect Answer - Pridať príspevok" FontSize="24px" HorizontalAlignment="Center"></TextBlock>
            <TextBox x:Name="txtPost"
                     Grid.Row="1"
                     Margin="8"
                     HorizontalAlignment="Center"
                     Height="100"
                     TextWrapping="Wrap"
                     MaxLength="512"
                     MinHeight="100"
                     MaxHeight="100"
                     MinWidth="500"
                     MaxWidth="500"/>
            <TextBlock x:Name="textStatus"
                       Grid.Row="2"
                       Text="Svoj príspevok napíšte hore" FontSize="16px" HorizontalAlignment="Center"></TextBlock>
            <Button x:Name="btnRegister"
                        Grid.Row="3"
                        Content="Pridať tento príspevok"
                        Margin="8"
                        Background="LimeGreen"
                        Foreground="Black"
                        HorizontalAlignment="Center" 
                        Click="btnPost_Click"/>
        </Grid>
    </Grid>
</Page>