Here is mine. You can copy past it if you like. Make sure that you can see the new view you add in your grid layout view. it might be off screen. Change your positioning as you need it. This is currently set for middle bottom.
<DrawingSurfaceBackgroundGrid x:Name=“fDrawingSurfaceBackgroundGrid” Grid.Row=“1” Margin=“12,0,12,0”>
<corona:CoronaPanel x:Name=“fCoronaPanel”>
<UI:AdControl x:Name=“ad1”
ApplicationId=“LALALA not telling you”
AdUnitId=“or this either”
HorizontalAlignment=“Center”
Height=“60”
Margin="-0,-10,0,0"
VerticalAlignment=“Bottom”
Width=“320”
IsAutoCollapseEnabled=“True”/>
</corona:CoronaPanel>
</DrawingSurfaceBackgroundGrid>