Twitter Help Center | How To Use Twitter With Facebook

Twitter Help Center | How To Use Twitter With Facebook: ":

Log into the Twitter account you wish to associate with your Facebook profile
In a new tab or window, log into the Facebook account you wish to have your Twitter updates posted to.
Navigate to the Applications page http://apps.facebook.com/twitter/
When asked, “would you like to connect your Twitter and Facebook Accounts?” as shown in the image below, select ‘allow.’"