How to Select Next node using linq in xml?

hi guys... I got this problem...
I've created 4 buttons that their names are first, next, previous, last.
what i want is that when the user clicks the first button the application throws a messageBox showing the values of the first book and when the user clicks next to show in another messageBox with the next book of my xml document, the same with previous and last...
i got this xml:

<?xml version="1.0" encoding="utf-8"?>
<books>
  <book>
    <title>Beginning Visual C#</title>
    <author>Karli Watson</author>
    <code>7582</code>
  </book>
  <book>
    <title>Professional C# 2nd Edition</title>
    <author>Simon Robinson</author>
    <code>7043</code>
  </book>
  <book>
    <title>Beginning XML</title>
    <author>Fawcett</author>
    <code>1500</code>
  </book>
  <book>
    <title>Silverlight 5</title>
    <author>Diaz</author>
    <code>1501</code>
  </book>
  <book>
    <title>Professional Silverlight 4 in c#</title>
    <author>MacDonald</author>
    <code>1502</code>
  </book>
</books>

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and i got this code:

//first button
            XElement xEle = XElement.Load(@"C:\books.xml");

            var emp1 = xEle.Descendants("book").ElementAt(0);
            

            MessageBox.Show("Title: " + emp1.Element("title").Value + System.Environment.NewLine + "Author: " + emp1.Element("author").Value + System.Environment.NewLine + "Code: " + emp1.Element("code").Value);

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what can i do for the next button?