To create a discount group, log in as an admin, go to Settings → Groups and Memberships. Then click on "Create New Discount Group" and name it as desired.

To add a special price for this discount group, go to the price list by selecting Settings → Prices. Click on the price list you want to add the discount group to and select ‘+Discount Group’ on the far right. Then, enter the price you want the discount group to have for their portion of a booking.