Like iPhoto, your Photos for Mac library can run off an external hard drive. Make sure you've quit Photos for Mac, and the rest is easy! 
Launch a Finder window on your Mac. Click your Mac hard drive in the menu on left of the window (should be Macintosh HD). Click your user name. Click Pictures.
Jack Davis I just watched Kevin’s video about Photos. I haven’t been having a good time with Photos. It wasn’t until I watched his video until I figured out how to get back the iPhoto editing stuff (you need to click the Add button under Advanced!) I still have two things I can’t work out and was hoping that he might be able to help with this: 1) When you create a folder and then import your photos they don’t go into the folder, even if it is in focus, instead they go into the Last import (with iPhoto when you imported the photos they automatically went into a new event) So how do I import into my newly created folder?
2) With iPhoto there was a little info frame on the left hand side that showed you the filename etc. Is there any way to get that back? Regards, Jack •.