modifying string content of XML file in CDATA block

Question

Hi,

How can i modifying the string content in CDATA block of an XML file, such as

For reference[(text)] please look below syntax,

        <![CDATA[<FlowDocument FontFamily="Helvetica" FontSize="24"
            Foreground="#FFFFFF00" TextAlignment="Left" PagePadding="5,0,5,0"
            AllowDrop="True" xmlns="http://xyz.com"&gt;&lt;Paragraph&gt;&lt;Run
            FontFamily="Helvetica" FontSize="62" Foreground="FF00B38D"
            xml:lang="en-gb">***This is for Testing purpose***</Paragraph>]]>

Thanks, Lenin