Drag a Marker on to the Map. You could have two, a green one for your location and a red one for your destination. The Blocks below show one way to use the two Markers.
I don't understand. For your campus app you need either a List of destination coordinates to select from or two TextBoxes (one to provide the destination latitude and one to provide destination longitude)
No. The start location is provided by the user's gps. TextBox1 and 2 are used in the example to provide a destination lat and lon manually. If you have a List of destination locations (coordinates) you should use a ListView or ListPicker for the user to select where they want to go. You then will not need to use the TextBoxes at all. 
Here is an example possibly suitable for your campus app that might help you construct your app:
