Reader Stephen Love writes in about uploading photos that are stored in Photos or iPhoto to websites. He knows he can navigate to a photos library—an OS X package that can be opened—and find media inside there. But he wants to be able to select images as they appear in Photos or iPhoto.
You should be able to use a media browser, sometimes labeled or described somewhat differently among various Apple software, desktop user interface, and third-party apps. In Pages and iMovie, there’s a labeled option to browser your main and alternate media library, including offering options for both iPhoto and Photos if you’ve retained libraries in both formats.
Read more here:: How to upload a photo from Photos for OS X to a website