To complete a purchase with Wit Points, you select a product you wish to purchase from WiseShop and select ADD TO CART for the product. When you're done shopping and ready to checkout, select "Checkout" from your SHOPPING CART. If you scroll down to the "Payment method" pane of the Checkout form, you will see that there is a radio button available to pay by Wit Points. It will show the amount of dollars you have available for the purchase based on the Wit Points you've accumulated. This balance is based on an exchange rate of about 10 Wit Points to a $1. If you select Wit Points, it will apply those Wit Points to your purchase.
