This is more a setup guide and does not cover how to use facebook developer tools, official documentation can be found at official docs for Facebook Instant Games
First Things First:
Make sure you are using the beta version of Construct 3
Add the Facebook Instant Games object to your game
Add the Facebook object to your game (set app id and secret key in object inspector) [not sure if needed, but necessary if you want to access profile picture, id etc.]
IMPORTANT NOTICE:
You need an Apple Team Id before you can publish your games for review. This costs $99 per year for an individual.
Basic Setup Under Facebook Developer:
1. Create an app
2. Scroll to Add Product: click setup under Instant Games
3. Setup all information under Instant Games > Basic Details
4. Upload your exported build under Web Hosting
To test your application:
Create a test app from your main one.
1. Click create a test app under Web Hosting (see image)
To be able to see the test app in your facebook instant games list for testing you must setup Instant Games and fill in the basic details for the test app also (otherwise it won't show up under development in instant games on Facebook).
1. On the main dashboard in developer.facebook.com, scroll down to Add A Product:
2. Click "Set Up" button under Instant Games (see image).
BEFORE YOU PUBLISH FOR REVIEW
1. Make sure you have tested your app on a range of different devices, mobile, tablet, pc etc.
2. If using webgl effects its worth using 'if mobile device' turn them off to improve performance.
3. Consider matching the resolution to the device.
4. Consider orientation.