This blog defines how to use Popup Control in
WPF.
<Window
x:Class="LayoutDemo.wndPopup"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="wndPopup"
Height="300"
Width="300">
<Grid>
<ToggleButton
IsChecked="{Binding
ElementName=pup, Path=IsOpen}"
Content="Open
Popup" Margin="100"
/>
<Popup
Placement="Bottom"
AllowsTransparency="True"
PopupAnimation="Fade"
x:Name="pup"
VerticalOffset="-100">
<StackPanel>
<TextBlock
Name="McTextBlock"
Background="Black"
Foreground="White"
>
This is popup text
</TextBlock>
<Button
Content="Close
this Pupup" Click="Button_Click"/>
</StackPanel>
</Popup>
</Grid>
</Window>