My hard drive recently crashed. I had backups of everything important to me, mostly pictures, on an external hard drive and also ICloud. My question is when I click on the external hard drive--users--pictures. I have about 10 yrs of pictures on it. But when I click on the Mac HD and select Photos there are only about 6 months of the most recent pictures in the new Photo application (used to be IPhoto). So when I try to move the pictures from the external HD to the picture application on the left side they don't show up in Iphoto. How do I move them from my external HD to the new internal Mac HD and be able to view them in a slide show and edit them like I can in Photos?