Typo in my last comment: I editted the configure.php files (not the configuration.php files).

I havenow succeeded in getting the "https" into my ZC URLs so I though that I would proceed with installing PayPal, but I found that I don't have the "https" in front of the IPN Preferences URL (....../ipn_main_handler.php) or the Automatic Return URL (............/index/php?main_page=checkout_process).

Is there any other ediiting that I can do to get the SSL to apply?