You can use the Affiliates Manager plugin with Simple Shopping Cart Plugin so that affiliate commission is given to the affiliates that send you visitors to your store/site.
The affiliate manager plugin has built in integration with Simple Shopping Cart plugin so you don’t need to do anything special.
Simply activate these two plugins on your WordPress powered site. After that, you will be ready to start accepting affiliate registration on you site.
Your affiliates will be able to send traffic to your store/products page and get rewarded for it when a customer (referred by the affiliate) purchase a product via the simple cart system.
When you receive orders in simple shopping cart, the affiliate plugin will award commission to the appropriate affiliate (if applicable).
Please post your question on the forum if you face any issue setting up the plugin.