I created a new content type in Drupal 7 and I want to make a template to customize the node add page for that content type. I want to be able to check if the user is authenticated with Facebook before they can use the node add form. If user is not authenticated then I will show them a paragraph explaining that they need to authenticate via facebook before they can use this form. I want them to always see the form link but they can only use the form if they are authenticated to facebook. I just don't know where to put it. Is it possible to make a template file specifically for that node add page so that I can include my logic?
Hiding options such as publishing and URL aliases is accomplished through the use of user roles and permissions. Visit
/admin/people/permissions on your site to see what I mean. Enable the help module for more (contextual) assistance.
If you want to perform additional modification beyond basic access control, then, seeing as to how you are attempting to customise a form, you would need to implement a Drupal hook named hook_form_alter(). You will need to do this in a custom module - if you haven't done this before, it's a lot easier than it sounds :)
There should be plenty of information and guides on SE, d.o as well as Google on how to use this hook to modify forms. But the one reference that you definitely need to be aware of is the Form API reference.
Since you want links to the node-add form to be visible, rather than controlling access to the page based on the FB-authentication status, you can check the status during the form_alter and either add a message and disable the form, or as is usually done, set an error message or notice (using
drupal_set_message()) and redirect them to a page where they can log in via FB; the message/notice will be displayed at the destination.