How to program button

I would like to insert a button into this page - propertytech.org/node/20/quiz/ so that the visitor could click the button to start the quiz in addition to the tabbed link at the top of the page. It appears to want a link to /node/20/quiz/start
I am feeling really poorly in not knowing how to insert the action into the php to get this button to appear (I have set up the cck field) and then work.

Thanks

Rob