To Add a Product:
Go to Sites > Funnels > Select Funnels > Products >+ Add Product > Add Product Info > Save.
The process of setting up an affiliate product is no different than setting up any other product within a funnel or website.
The only difference is that you would move to the Affiliate Manager Campaign Settings once the funnel has been setup and filter down to the specific product and funnel/website you just created (see image below).