Your XML is not well formed, CDATA should be as follows;
<value><![CDATA[24.34]]></value>
NOT
<value><![CDATA[24.34</value>
XML elements and nodes are selected using XPath - refer below link;
XML and XPath[
^]
Easiest method of getting the exact nodes you want is;
XmlDocument myDoc = new XmlDocument();
myDoc.Load("<file name and path>");
XmlNodeList nodes = myDoc.SelectNodes("//param_list[@name=\"SegmentName\"]/value");
The nodes object will contain the 2 value nodes
To access the actual text values & show in a Message Box you can loop through the nodes as follows;
foreach(XMLNode node in nodes)
{
MessageBox.Show(node.InnerText);
}
Kind Regards