Add this code in your xaml
<Popup x:Name="Popupsample" IsLightDismissEnabled="True">
<Border BorderBrush="#FFBD00" BorderThickness="3">
<StackPanel x:Name="DeleteStackpanel" Height="120" Width="270" Background="White" Orientation="Vertical">
<TextBlock x:Name="DeleteTextblock" TextWrapping="Wrap" Width="220" FontSize="17" Padding="5 20 5 0"></TextBlock>
<Button x:Name="DeleteButton" Click="DeleteButton_Click_1" Margin="0,15,20,0" x:Uid="DeleteContentBtn" Background="#FFBD00" HorizontalAlignment="Right"></Button>
</StackPanel>
</Border>
</Popup>
and call Popupsample->IsOpen = true.