Problem to display listBox.Items.Add in ListBox

Question

Hello,

I've in my C# class:

1. foreach (var item in horaires)
2. {
3. var Objet = item.Horraire.ToString();
4. listBox.Items.Add(Objet);
5. }

And in my XAML:
<ListBox x:Name="listBox" Grid.Row="1"/>

My data are great, but I would custom my ListBox with:

1. <ListBox.ItemTemplate>
2.         <DataTemplate>
3.                 <Border BorderBrush="White" Margin="0" BorderThickness="0,0,0,0.5">
4.                         <StackPanel Orientation="Horizontal" Margin="0,5,0,5" VerticalAlignment="Top">
5.                                 <TextBlock Text="{Binding item}"

6. Name="item"

7. FontSize="36"

8. VerticalAlignment="Top"

9. TextAlignment="Left"

10. TextWrapping="Wrap"

11. Width="340"/>

12. </StackPanel>

13. </Border>

14. </DataTemplate>

15. </ListBox.ItemTemplate>

But With, my data don't show. So, How to display my data with this model?
I would like make listBox.Items.Add(Objet); in my TextBlock Name="item"

Thanks for your helps.
Valentin