To connect your Twitter account and your Facebook profile:

1. Log in to the Twitter account you want to associate with your Facebook profile.
2. Go to your Settings menu’s Profile tab.
3. Scroll to the bottom and click Sign in to Facebook and connect your accounts.
4. When prompted, select the privacy settings for who will see your Tweets posted to your Facebook wall. It is set to public by default.
5. Click Log in with Facebook and enter your Facebook login credentials.
6. Click Allow to accept permissions.
7. Your Tweets will now post to your profile Facebook wall and your username will be displayed there as well. @Replies will not be posted.

If you have a Facebook Fan Page, or are the admin of one, you can post Tweets from your Twitter account to your Facebook Page.

1. Follow the steps above to connect to your Facebook profile.
2. In your Twitter profile settings page, Select the page you’d like to connect to.
3. When prompted, click to allow permission to post to the selected Facebook Page. and you’re done 🙂

source: twitter