Thanks for posting in the Apple Support Communities AndyC44,
If you've moving from PC, you might find the following resource helpful: Move your data from a Windows PC to a Mac
If you're importing Photos app, the following steps should help:
Import from a hard disk, optical disc, or flash drive
You can import photos or video files from a storage device (such as a hard disk), a CD or DVD (if you have an optical drive), or a flash drive.
Important: Don’t eject a camera or device while the photos or videos are being imported.
1. Connect the device to your Mac.
2. In Photos, choose File > Import, then select the items you want and click Review for Import.
3. To set where to import the items, click the Album pop-up menu and choose a location.
4. Note: If you participate in an iCloud Shared Photo Library, choose Your Library or Shared Library from the Add To pop-up menu.
5. If you selected a folder that contains other folders, choose Library (you can’t import a group of folders into an album).
6. Do one of the following:
* If you selected multiple photos or videos, click Import All New Photos, or select the ones you want to import and click Import [number] Selected.
* If you selected a folder of items that contains other folders organized in a way you want to maintain, select the Keep Folder Organization checkbox, then click Import All New Photos.
Imported photos appear in the Imports and Photos albums in the sidebar.
Import photos from storage devices and DVDs using Photos on Mac
Cheers!
