Create a conversion
Go to your Conversions page, click on the “New Conversion” button to create a new conversion.
A window will appear where you will specific the affiliate you'd like to attribute the conversion to, the external id, and conversion amount (the transaction amount). If you're using lifetime/recurring commissions, you can also set the customer id in this window.
Create a Customer
Go to your Customers page, click on the "New Customer" button to create a new Customer.
A window will appear where you will specific the affiliate you'd like to attribute the conversion to, customer id, and what your customer flow is. You also have the option to add metadata here.
Note: If you're uncertain what the difference is between a conversion and a customer, you can refer to this article: Understanding Customers vs. Conversions.