Please see this.
Text inside a CDATA section will be ignored by the parser.
http://www.w3schools.com/xml/dom_cdatasection.asp
This is will help you to understand the basics about XML
Just put the html tags with there content and add the xmlns attribute with quotes after the equals and in between the quotes is http://www.w3.org/1999/xhtml
The purpose of BASE64 encoding is to take binary data and be able to persist that to a string. That benefit comes at a cost, an increase in the size of the result (I think it's a 4 to 3 ratio). There are two solutions. If you know the data will be well formed XML, include it directly. The other, an better option, is to include the HTML in a CDATA section within an element within the XML.
so long as your html content doesn't need to contain a CDATA
element, you can contain the HTML in a CDATA
element, otherwise you'll have to escape the XML entities.
<element><![CDATA[<p>your html here</p>]]></element>
VS
<element><p>your html here</p></element>
Source: Stackoverflow.com