Hi!
How can I include zenphoto in my web page?
My navigation works something like this:

The best way to integrate into an existing WEB page is to make a theme with the look and feel of the rest of the site. Then you just place a link to www.mypage.com/zenphoto/

From the text of your error message it would appear that you are not using the 1.1 release (the zen folder was changed to zp-core in that release.) There is no line 645 in the current version of classes.php

You might want to download the current version and try it. You should also check the chmod settings of your albums folder. It needs to be @777