I understand that you want to retrieve some photos that were backed up. I'm happy to provide some help for this.
Getting your photos will depend on how they were saved. If you created a backup, but you were using iCloud Photo Library, you'll want to enable iCloud Photo Library on your device to download your photos:
If the photos were not synced with iCloud Photo Library, then you'll need to restore the backup that contained those photos since you cannot pick individual files out of the backup: