In order to connect your UberSocial to Facebook and have your tweets posted to your FB wall, you'll first need to sign in. To get started, click the "F" icon on your UberBar or find the Facebook section in your UberSocial Options. After this, you will be redirected to the Facebook login site where you can type your email and password to sign in. See below:
Once you click "Log In", you will be taken back to UberSocial when your timeline will be retrieved.
At this point, you are now ready to post to FB. Just go to the tweet compose screen and type your tweet, but don't forget to activate the small "f" icon on the task bar above. When the "f" icon arrow is green, the tweet will post to FB. When it's left gray, the tweet will only update your Twitter status.