how to use xmldocument?

Hello I want to make an xmldocument object not to be saved in a file. How do I use create element so that I get different levels of the nodes? Like this:

Code:

---

<root>
  <node1>
        test
  <\node1>
<\root>

---

I used these logic to read xml from a databse:

Dim strSQL As string = "SELECT OrderId, OrderDate FROM Orders FOR XML AUTO,
ELEMENTS"

Dim xReader As New XMLReader()
'...ADO.NET code to get a XMLReader

Dim doc As New XMLDocument()
doc.Load(xReader)
xReader.Close()

An exception generated in line doc.Load(xReader) because there is no root
node in the result XML. Query the XML directly from SQL Query Analyser, I
can get there:
<Orders><OrderId>10248</OrderId><OrderDate>1996-07-04T00:00:00</OrderDate>
</Orders>
<Orders><OrderId>10249</OrderId><OrderDate>1996-07-04T00:00:00</OrderDate>
</Orders>