Help creating special voucher/promo code

[Sbeirach]

I am trying to create a special promo code/ voucher that will give a customer 10% off if they buy 6 items from certain areas.

 

This is what I am trying to do. The 6 items must include a backpack, and for the other 5 items, they have a choice of sleeping bag, sleeping pad, hydration bladder, water bottle, mess kit, or head lamp.

 

How do I set this up? I have been trying for over a week now but no luck.

 

 

Thanks for your help.