I like to integrate Constant Contact API into Joomla, i had created the test account and i had your php zip content but i cant understand how can i integrate that into joomla. Kindly reply asap.
The Joomla plugin you are asking about is not a Constant Contact integration. It was done by a 3rd party developer and provided for free to internet users. You would want to get in touch with that developer if you have questions on the usage or installation of the product.