How to set the right start location

Question

how can i set my way points to be known; this is my code:

// setup the waypoints

Waypoint wpStart = new Waypoint();

wpStart.Location = start;

wpStart.Description = "Crane Bank US";

req.Waypoints = new System.Collections.ObjectModel.ObservableCollection<Waypoint>();

req.Waypoints.Add(wpStart);

Waypoint wpEnd = new Waypoint();

wpEnd.Location = destination;

wpEnd.Description = "watoto";

req.Waypoints.Add(wpEnd);

// display start and destination with pushpins

map1.Children.Clear();

Pushpin p = new Pushpin();

p.Location = wpStart.Location;

p.Content = wpStart.Description;

p.Background = new SolidColorBrush(Colors.Red);

map1.Children.Add(p);

p = new Pushpin();

p.Location = wpEnd.Location;

p.Content = wpEnd.Description;

p.Background = new SolidColorBrush(Colors.Blue);

map1.Children.Add(p);

// start the route calculation

rc.CalculateRouteAsync(req);