C# WPF MVVM viewmodel App.xaml OnStartup calling more than one call

[stealthrt]

Hey all I am terrible at MVVM so I hope someone more knowledgeable will be able to answer my question.

I have a app that, when started, first calls the view model (App.xaml) and calls a function that passes images from a folder(s). The issue being that I am unsure how to call more than just that one call:

protected override void OnStartup(StartupEventArgs e)
{
    base.OnStartup(e);

    string boxPath = Environment.CurrentDirectory + @"\boxes";
    // set the update interval
    var imageSource = new ImageSource(Path.Combine(boxPath, "box1"), TimeSpan.FromHours(1));
    var viewModel = new MainWindowViewModel(imageSource);
    var window = new MainWindow()
    {
        DataContext = viewModel
    };

    window.Closed += (s, a) => { viewModel.Dispose(); };
    window.Show();
}

The code ImageSource(Path.Combine(boxPath, "box1"), TimeSpan.FromHours(1)); is what I am in need of modifying so that I can include calls for all my boxes (1-10) instead of just that one.

How would I modify this in order to call more than one box1? I'd really rather call the boxes from a viewmodel instead of inside the app.xaml but I am not sure if that's possible or not?