You can select your privacy level very easily by clicking the user menu which can be accessed by clicking on the "person" button at the top right hand corner of the page. If you have uploaded a profile photo and it has been approved, then simply click your profile photo button at the top right hand side of the page. You will then be presented with a menu - simply click the "My Settings" link. Then select the "Privacy" Tab, its quite self explanatory.
Below is a list of privacy options you can select to limit who can view your profile, posts etc. Each offers a different level of privacy as shown below.
Everyone - Viewable by visitors, bots and the world.
Registered Users - Viewable only by logged in members.
Friends - Viewable only by people on your friends list.
No-one - Viewable only by you.
To alter your privacy settings please click here.