Add folders to Photos
To do this, you’ll need to enter the Photos app’s settings. Find this by dropping down the ellipsis (…) menu at the top right of the interface. Choose ‘Settings’, and the first thing you see will be labelled Sources. Click ‘Add a folder’ and head to the folder you keep your photos in. Hit ‘Add this folder to Pictures’ then back out of Settings to the Collection view to see the newly added photos.