title: Best way to read, modify, and write XML
body: <p>My plan is to read in an XML document using my C# program, search for particular entries which I'd like to change, and then write out the modified document.  However, I've become unstuck because it's hard to differentiate between elements, whether they start or end using XmlTextReader which I'm using to read in the file.  I could do with a bit of advice to put me on the right track.</p>
  
  <p>The document is a HTML document, so as you can imagine, it's quite complicated.</p>
  
  <p>I'd like to search for an element id within the HTML document, so for example look for this and change the src;</p>
  
  <pre><code>&lt;img border="0" src="bigpicture.png" width="248" height="36" alt="" id="lookforthis" /&gt;
  </code></pre>