Go to Marketo Admin.
Go to LaunchPoint, click on New and select New Service.
Enter a Display Name for your service and select the Facebook Custom Audiences service from the Service drop-down.
Open a new tab in the same browser and go to www.facebook.com. Log into Facebook using the account you want to use for the integration.
After you're logged into Facebook, return to Marketo. Click Authorize.
If prompted, click OK to accept the Marketo app installation into Facebook.
You're now authorized! Select a matching mode and click Create.
Great job! You can now go over to any static or smart list in Marketo and send audience data over to Facebook.