How can I data bind a list of strings to a ListBox in WPF/WP7?

I am trying to bind a list of string values to a listbox so that their values are listed line by line. Right now I use this:

<ListBox Margin="20" ItemsSource="{Binding Path=PersonNames}">
    <ListBox.ItemTemplate>
        <DataTemplate>
            <StackPanel Orientation="Horizontal">
                <TextBlock Text="{Binding Path=Id}"></TextBlock>
            </StackPanel>
        </DataTemplate>
    </ListBox.ItemTemplate>
</ListBox>

But I don't know what I am supposed to put into the textblock, instead of Id, since they are all string values, not custom classes.

Also it complains not having to find the PersonNames when I have it inside MainPage, as MainPage.PersonNames.

I set the data context to:

DataContext="{Binding RelativeSource={RelativeSource Self}}"

I am doing it wrong?