You need to be loged in on facebook and then follow this 2 steps:
Go to your address bar and copy link from second step and paste it to notepad or any text editor. Result will be something like this:
This BOLD code is your access token.
Copy it and paste it to field for Login via Access token and you can continue with using Total Auto Poster.
WARNING: Link in this post is my link. You need to click on steps as described and to copy/paste YOUR url to text editor, to get to Access token.