Once you’re signed into your Smashcast account, go to the Profile > Connections page
Here you’ll see all the options of what you can connect Smashcast to
Select the “Connect” button beside Facebook and follow the prompts in the pop-up window
If you want to disconnect your Smashcast account from Facebook, you’ll need to go to your Facebook page, go to Settings > Business Integrations > from there you can find Smashcast in either Active or Removed, or search for it in the search bar at the top, and then select remove.
(As of June 13, 2018)