If you have downloaded the distribution you have the inc_features.php.
You must have overlooked the install instructions on photopost as they are clearly visible on the main page of the site under support in the manual
http://www.photopost.com/installphp.html
As far as the inc_features.php included in the distribution there is instructions on that in the product faq forum here
PhotoPost Enhanced vB3 Index Integration
without you stating a site or error I can not suggest anything to fix your problem