In El Capitan, iPhotos was replaced by Photos.
When you first open Photos on your Mac, your photo library is upgraded. The upgraded library is compatible with both Photos and iPhoto (if installed), but any changes you make in Photos won’t appear in iPhoto, and vice versa.
If you can take a minute and use the rating system to rate our session as 3 stars or higher and press Submit so I am credited with helping you.
If you open a picture, it will open in the Photo app.