XAML:
<ComboBox x:Name="ComboBox" ItemsSource="{Binding myListofItems}" HorizontalAlignment="Left" Margin="256,41,0,-6" VerticalAlignment="Top" Width="108" Height="26" FontSize="13" />
C#:
public partial class MainWindow : Window, INotifyPropertyChanged
{
    private List<string> _myListOfItems = new List<string> ();
    public List<string> myListOfItems
    {
        get { return (_myListOfItems); }
        set
        {
            _myListOfItems = value;
            OnPropertyChanged ("myListOfItems");
        }
    }
    public event PropertyChangedEventHandler PropertyChanged;
    protected void OnPropertyChanged(string propertyName)
    {
        var handler = PropertyChanged;
        if (handler != null) {
            handler (this, new PropertyChangedEventArgs (propertyName));
        }
    }
    public MainWindow()
    {
        InitializeComponent ();
        this.DataContext = this;
        // Start Populating your List here
        // Example:
        for (int i = 0; i < 10; i++) {
            myListOfItems.Add (i.ToString ());
        }
    }
}