It is very easy to use ShopBack GO, simply follow these steps:
Step 1: Add a debit or credit card to your ShopBack Account
Step 2: Tap on "Activate Offer" to activate Cashback for a specific outlet
Step 3: Visit the outlet before the offer expires
Step 4: Pay as per normal with the same debit or credit card
Step 5: Get Cashback! Repeat as many times as you like
or see here for more detailed instructions!