Your profile has a range of privacy settings that you can adjust to meet your needs regarding networking and visibility.  To edit your privacy settings on your profile you must be logged in.  Go to Profile in the Community menu and mouse over it.  Select Edit Profile.

PrivacySettings3

 

On the right hand side, you'll see a small globe icon.  Click on that to adjust whether you wish that field to be visible to the public - visitors who aren't logged into the site - Site Members, Friends, or only yourself.

  PrivacySettings2

Once you have made the changes, scroll down to the bottom and click on the SAVE CHANGES button.