The default is to take you back to the forum you just posted in. If you want to be taken back to the thread you just posted in as if to look at your post you just made, that setting is in your profile.
*Click on the "profile* button.
*In your profile, click on "Look and Layout Preferences", which is on the left side of your screen.
*On that page you put a check in the box next to "Return to topics after posting by default"