This is how to review your privacy settings

1. Click on your profile picture to the lower right.
2. Click on the hamburger icon to the upper right.
3. Click on Settings.
4. Click on Privacy and Security.  

This is how you make your account private

1. Click on your profile picture to the lower right.
2. Click on the hamburger icon to the upper right.
3. Click on Settings.
4. Click on Privacy.
5. Click on Account Privacy. 
6. Click on the switch button next to “Private Account”.

If you have a private profile, only the people who follow you can see your posts. A private profile also means that the people who want to follow you have to send you a request first that you can accept or reject.