Hi guys,
Thanks for the help tydust.
For preview feature to work you only need to point to your Joomla install.
So if you see your Joomla install in your broswer
http://localhost:8888/joomla thats what you put into the field.
as for mapping to the template folder you need to find your Joomla install
and just map it to your the templates folder in your local hard drive
macHD:MAMP:doc:joomla:templates etc..
Cheers,
Brian