To enable support for Shopp, go to Affiliates > Settings > Integrations and check the box that says Shopp:

Screen Shot 2014-04-07 at 3.07.58 PM

Once enabled, AffiliateWP will automatically generate referral records when customer is successfully referred to your store via an affiliate link.

In Affiliates > Referrals, the Reference column refers to the order ID in Shopp:

Screen Shot

Clicking on the Reference column will take you directly to the order details page in Shopp.

In the Order Notes section of the Edit Order screen will be a note indicating a referral was created for the purchase.