Membership can be activated in the Main window's Control Panel > Required Settings.  You can set the standard member discount from 0 upwards. On this Members windows besides the members particulars you can set the discount (DiscountPlus) over and above the standard discount. A Referrer name can be added to work out the commission for the referrer based on the member's purchases.

Members' purchases can be easily generated using the buttons on the lower right corner.