how to make facebook private?

[john]

Head to your privacy settings under the Account menu at the upper right corner of your Facebook page.

On the privacy settings page, you'll see five categories: Profile, Contact Information, Applications and Websites, Search and Block List.

Start at the top with Profile information and change all the options to "Friends." This will stop people you don't know from accessing any of your personal data.
Do the same for your contact information, most of which, thankfully, still defaults to Only Friends.

Also be aware that each setting has a "customize" option which allows you to, for example, set your information to "visible only to friends" but also block certain "friends" (like your mom, so she won't see the drunken, late night rants you post on your Wall).