Here are a few simple steps to add a form of payment in your Facebook Ads account: 

  1. Confirm you are the admin on the Facebook Ads account as this is required in order to make changes to the account's payment methods. Learn how to gain Admin Access here. 
  2. Click Payments under Business Setting in Ads Manager.
  3. Click +Add under Payment methods.
  4. Choose the payment method that you want to add, fill in your information, then click Continue. Follow any additional instructions to add your payment method. 

Click here to learn how to grant Winnow access to your Facebook Ads account.