XmlWriter

using (IsolatedStorageFile isoStore =
    IsolatedStorageFile.GetUserStoreForApplication())
{

    // Create new file
    using (IsolatedStorageFileStream isoStream =
        new IsolatedStorageFileStream("IsoStoreFile.xml",
            FileMode.Create, isoStore))
    {
        // Write to the Isolated Storage for the user.
        XmlWriterSettings settings = new XmlWriterSettings();
        settings.Indent = true;
        // Create an XmlWriter.
        using (XmlWriter writer = XmlWriter.Create(isoStream, settings))
        {

            writer.WriteComment("sample XML document");

            // Write an element (this one is the root).
            writer.WriteStartElement("book");

            // Write the namespace declaration.
            writer.WriteAttributeString("xmlns", "bk", null, "urn:samples");

            // Write the genre attribute.
            writer.WriteAttributeString("genre", "novel");

            // Write the title.
            writer.WriteStartElement("title");
            writer.WriteString("The Handmaid's Tale");
            writer.WriteEndElement();

            // Write the price.
            writer.WriteElementString("price", "19.95");

            writer.WriteStartElement(null, "ISBN", "urn:samples");
            writer.WriteString("1-861003-78");
            writer.WriteEndElement();

            // Write the style element (shows a different way to handle prefixes).
            writer.WriteElementString("style", "urn:samples", "hardcover");

            // Write the close tag for the root element.
            writer.WriteEndElement();

            // Write the XML to the file.
            writer.Flush();
        }
    }
    // Open the file again for reading.
    using (StreamReader reader =
                    new StreamReader(isoStore.OpenFile("IsoStoreFile.xml", FileMode.Open)))
    {
        OutputTextBlock.Text = reader.ReadToEnd();
    }

    // Delete the IsoStoreFile.xml file.
    isoStore.DeleteFile("IsoStoreFile.xml");
}