HTML button with Jquery Under CDATA

I was wondering how would I implement javascript/jquery and html in the CDATA section of an XML. Im trying to create a gmail contextual gadget and this is the first time I had to deal with CDATA section in XML.

Basically I want to create a simple button when clicked will display a hello world perhaps.

EDIT

I found out that there is some extensive documentation on what I wanted to accomplish http://code.google.com/api开发者_开发百科s/gadgets/docs/ui.html

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http://code.google.com/apis/gadgets/docs/ui.html