Integrating your a Facebook page with a campaign is easy. Just go to the campaign you want to integrate by selecting it in the campaign dropdown on the left under the navigation or in the list of campaigns in the main page, then settings / integrations.
You will see the list of the different integrations possible.
Click on "Authorize" in the Facebook box. You will be redirected to Facebook to authorize your account linked. You will be then redirected back to the integration interface.
Then choose your account in the account dropdown, then the page you want to analyze.
Click Save Changes.
You can change the integration by clicking Manage, or totally disconnect the account by clicking Disconnect.