Think of this like the query window Sql manager, a way to write your XPath query and see the results of it. It also provides a nice view of what's going on.
If you don't understand XPath please read the refrence here and test it out with the tool.
Using the code
Since there is still no way to paste code to into this article in an easy way I will post each individual tough nugget in an seperate tip and trick where the editor works.
Thanks for your patience!