public class GpxFileDataAdapter :
    FileDataAdapterBase,
    IListSource,
    IGpxOptionsProvider

Public Class GpxFileDataAdapter
    Inherits FileDataAdapterBase
    Implements IListSource,
               IGpxOptionsProvider

private void Form1_Load(object sender, EventArgs e) {

    ImageLayer imageLayer = new ImageLayer() {
        DataProvider = new BingMapDataProvider {
            BingKey = "Insert_your_BingKey_here",
            Kind = BingMapKind.Road
        }
    };
    mapControl1.Layers.Add(imageLayer);

    VectorItemsLayer vectorLayer = new VectorItemsLayer();
    mapControl1.Layers.Add(vectorLayer);

    GpxFileDataAdapter dataAdapter = new GpxFileDataAdapter();
    dataAdapter.FileUri = new Uri(GetRelativePath("boston-marathon-course.gpx"));
    vectorLayer.Data = dataAdapter;

    dataAdapter.CreateRoutePoints = true;

    // Use the ItemsLoaded event to customize items the adapter generates.
    dataAdapter.ItemsLoaded += OnDataAdapterItemsLoaded;

    // You can call the MapControl.ZoomToFitLayerItems method in the DataLoaded event handler
    // to zoom the map so that it displays all vector items.
    vectorLayer.DataLoaded += OnVectorLayerDataLoaded;
}

private void OnDataAdapterItemsLoaded(object sender, ItemsLoadedEventArgs e) {
    foreach (MapItem item in e.Items) {
        if (item is MapPath) {
            item.Stroke = Color.Black;
            item.StrokeWidth = 2;
        }
        if (item is MapDot) {
            item.Fill = Color.Orange;
            item.Stroke = Color.Orange;
        }
    }
}

private void OnVectorLayerDataLoaded(object sender, DataLoadedEventArgs e) {
    mapControl1.ZoomToFitLayerItems(new LayerBase[] { mapControl1.Layers[1] });
}

public static string GetRelativePath(string name) {
    DirectoryInfo dir = new DirectoryInfo(Application.StartupPath);
    while (dir != null) {
        string filePath = Path.Combine(dir.FullName, name);
        if (File.Exists(filePath))
            return filePath;
        dir = Directory.GetParent(dir.FullName);
    }
    return string.Empty;
}

Private Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs)
    Dim imageLayer As ImageLayer = New ImageLayer() With {
        .DataProvider = New BingMapDataProvider With {
            .BingKey = "Insert_your_BingKey_here",
            .Kind = BingMapKind.Road
        }
    }
    mapControl1.Layers.Add(imageLayer)
    Dim vectorLayer As VectorItemsLayer = New VectorItemsLayer()
    mapControl1.Layers.Add(vectorLayer)
    Dim dataAdapter As GpxFileDataAdapter = New GpxFileDataAdapter()
    dataAdapter.FileUri = New Uri(GetRelativePath("boston-marathon-course.gpx"))
    vectorLayer.Data = dataAdapter
    dataAdapter.CreateRoutePoints = True

    ' Use the ItemsLoaded event to customize items the adapter generates.
    dataAdapter.ItemsLoaded += AddressOf OnDataAdapterItemsLoaded

    ' You can call the MapControl.ZoomToFitLayerItems method in the DataLoaded event handler
    ' to zoom the map so that it displays all vector items.
    vectorLayer.DataLoaded += AddressOf OnVectorLayerDataLoaded
End Sub

Private Sub OnDataAdapterItemsLoaded(ByVal sender As Object, ByVal e As ItemsLoadedEventArgs)
    For Each item As MapItem In e.Items

        If TypeOf item Is MapPath Then
            item.Stroke = Color.Black
            item.StrokeWidth = 2
        End If

        If TypeOf item Is MapDot Then
            item.Fill = Color.Orange
            item.Stroke = Color.Orange
        End If
    Next
End Sub

Private Sub OnVectorLayerDataLoaded(ByVal sender As Object, ByVal e As DataLoadedEventArgs)
    mapControl1.ZoomToFitLayerItems(New LayerBase() {mapControl1.Layers(1)})
End Sub

Public Shared Function GetRelativePath(ByVal name As String) As String
    Dim dir As DirectoryInfo = New DirectoryInfo(Application.StartupPath)

    While dir IsNot Nothing
        Dim filePath As String = Path.Combine(dir.FullName, name)
        If File.Exists(filePath) Then Return filePath
        dir = Directory.GetParent(dir.FullName)
    End While

    Return String.Empty
End Function