Sign up and Log in to the Business Manager Start page. Click Create a new Business Manager account and fill out the required fields with your business details.
Once you've filled out the required information, you'll be prompted to create a property for your app. Enter the desired name of the property for your app and click Go to Monetization Manager.
Indicate whether or not your app is live, check the This app is using mediation box and click Submit.
You will be prompted to create an ad placement for your application. Select a format, fill out the form and click Next.
The next step presents an overview of the placement you created. Take note of the Placement ID which will be used when setting up partner mediation.
In addition to the Placement ID, you'll also need the Facebook System User Access Token to set up partner mediation.
Log in to your Facebook developer account. Navigate to the My Apps page by clicking the My Apps button in the top-right corner. Add your app to the Facebook console by clicking the Add a New App button.
Fill out the form and click Create App ID to add your app to Facebook.
Note the App ID of the app you created. This value is used in the next step. You can always find your App ID from the My Apps page.
For connecting your app to a third-party mediation provider, see the documentation for the mediation partners you want to connect with.