If you aren’t logged into Snapchat, you’ll be prompted to do so.

If someone you’re not friends with sends you a snap, you’ll get a notification. If you add them as a friend, you’ll be able to see their snap.

You can also tap Custom to create a list of friends who can see your Story.

With these three settings configured, you’ve set your account to private and only your friends will be able to contact you, view your Story, and add you using Quick Add.