Read a node in config xml

[venerable bede]

I have the following in my confid settings:

<configuration>
  <appSettings>
  
    <add key="STAMP" value="999" />

  </appSettings>
</configuration>

If I want to alter the node 'STAMP' I do the following:

XmlElement elementStamp = (XmlElement)doc.SelectSingleNode("/configuration/appSettings/add[@key='STAMP']");
elementStamp.SetAttribute("value", "999");

What I want to know, and I know this is silly, but how do I read it?