If you’re the vendor, then you create your own product and set it up using Clickbank’s system. They then list your product in their marketplace so that tens of thousands of affiliates can see you. They handle the tracking using unique tracking links and cookies so they know exactly where the sale came from and credit the referring account accordingly.
With drop shipping, you’re effectively partnering with a manufacturer or wholesaler to sell their products. This way, you don’t pay upfront costs to buy inventory, aren’t sitting on unsold items taking up expensive warehouse space, and don’t have to deal with shipping the products yourself. You simply create your site, fill it with drop shippable products, and drive in customers, with almost everything else done for you.