When you write your journal, you always have options determine who can view the entry.  The options are:

“Everyone”, “My family and my friends”, “My family only” or “My friends only”

You can change the privacy setting at any time.  To change the privacy setting of an old journal entry, click "journal", find the journal entry that you would like to edit, click "edit" link under the journal, change the privacy setting, and click "Publish".  Your journal entry's newly updated privacy setting will take effect immediately.