Is it the navigation of your xml that's causing you trouble? The code you've linked seems to be able to work out a distance and add new rows to your response table, so I'm guessing that querying your xml is your problem.
If that's the case, then
System.Xml.XmlDocument.SelectNodes is the method you need - and you'll need to learn basic xpath.
Alternatively, you can search for "linq to xml" and there are plenty of good articles on how to query xml using linq.