Sign in to Facebook> Go to http://www.Facebook.com/Twitter
Facebook will then show you all the accounts you are an admin for, with a ‘Link to Twitter’ button beside.
Select the ‘Link to Twitter’ button for the fan page you want to link
You will then be re-directed to a new page where you will need to enter your Twitter account Username and Password and select Authorise app.
If the page only shows a ‘Authorise app’ button and ‘No Thanks’ button, check the top right hand side of your screen to make sure you are logged into the correct account you wish to link to.
Once you have Authorised the App you will then be directed back to the page before where you can then change your settings.
You can then go back to your fan page and start posting to both Facebook and Twitter.