This tutorial explains how to setup commission tracking as well as the steps that are needed to tracking specific types of commissions.
Commission Tracking Setup
To track commissions you must do the following:
The employee commission rate must be setup
If you are doing commission tracking off of invoices or payments the employee must either be manually added to an invoice or the option to automatically have an employee added to the invoice when the invoice is created must be selected.
If you are doing commission tracking off of events/sessions/appointments then the event/session/appointment must be linked to the invoice