In the task editor, click the link "configured social networks"
The connection box will appear:
Click "Connect to Facebook" - you will be taken to Facebook, login if not logged in already:
After clicking continue or logging in to another account you will be provided a list of Facebook Pages you have admin rights to. Select all of the ones you are likely to want to send updates to from your Task account:
After you click "Next" you'll be taken to a page to agree to the permissions requested - be sure to leave the permission as they are, any changes will cause the integration to fail:
Click "Done" - you may now find yourself asked to login in to Facebook again - don't worry, its just a double check to make sure it is you! Click login, and complete the Facebook login form.
You may find you are asked the same questions as above - just go through the process again, you should eventually see this success page:
Click "OK" - you should now be taken back to the original Task page - if not, just click back to the browser tab you originally came from before moving to Facebook - you should see a list of the Facebook Pages you selected previously:
Select the Page you'd like to post updates to - in this example I'll choose "Steve Test Page":
This will now show you the Page you are connected to, and a Disconnect button if you wish to cancel the connection.