When posting a journal, you have a few options on who can view your entry, who can comment and who can delete comments.

Everyone -  Any ONE looking at the site be able to read your deep dark feelings.
Members Only - Means lovely deviant memberss only.  Why would you want the outside world to know anyways.
Friends Only - Only people that are listed on your friends list are able to view.
Only Me - An online journal for yourself.

It's your preference if you don't want anyone to comment and just vent.  Just change the drop down to No Commenting.  If you have something to say but don't want everyone to read and respond, just change to Friends Only for both viewing and commenting.

 
^^^At the bottom of your journal screen under your mood and music section^^