Creating a specific XML document using namespaces in C#

<?xml version="1.0" encoding="UTF-8"?>
<Doc1 xmlns="http://www.sample.com/file" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xsi:schemaLocation="http://www.sample.com/file/long/path.xsd">
    <header>
        <stuff>data</stuff>
        <morestuff>data</morestuff>
    </header>
 </Doc1>

XmlDocument doc = new XmlDocument();
doc.LoadXml("<Doc1></Doc1>");
// Add nodes here with insert, etc...

XmlDocument doc = new XmlDocument();

  XmlSchema schema = new XmlSchema();
  schema.Namespaces.Add("xmlns", "http://www.sample.com/file");

  doc.Schemas.Add(schema);

using System.Xml.Schema;
using System.Xml;