Validate XPATH

hi guys,
i am start to learn XPath but i have problem , i am write my xml doc but i can not where i write my expression to find what i want from data ?

example

Code:

---

<?xml version="1.0" encoding="ISO-8859-1"?>
<bookstore>
<book>
  <title lang="eng">Harry Potter</title>
  <price>29.99</price>
</book>
<book>
  <title lang="eng">Learning XML</title>
  <price>39.95</price>
</book>
</bookstore>

---

====================================================
Path Expression || Result
====================================================
bookstore || Selects all the child nodes of the bookstore element
====================================================
/bookstore || Selects the root element bookstore
====================================================

Take a look at this example about xpath

http://www.codeproject.com/KB/cpp/myXPath.aspx

very good dannystommen , this through the API of .Net , but can i write any expression into notepad or any editor? if this can be....How ?

use the streamwriter class

Code:

---

        StreamWriter SR = new StreamWriter(@"C:\myDocument.txt");
        SR.Write("This is the content of the document");
        SR.Flush();
        SR.Close();

---