1. Navigate to Fundraising > eCommerce
  2. Choose the Stores tab
  3. Find your store in the list and choose the Edit option.
  4. Skip to step 8: Premiums.
  5. Choose Create New Premium with Purchase.
  6. Select a product to offer as your premium.
  7. Designate the Minimum purchase level for this premium.
  8. You can also choose whether or not to include standard shipping with your premium.
  9. Click Save.

See Configuring Premiums for the Store for more information.