site wide discount banner

Hello,

I will guide you on different tracks, but my answer won't be precise, as we need more elements to better understand your needs.
Anyway follow me step by step :
- First, you can create a module to display any kind of content and where you need to, see this tutorial .
- Second, have a look in HikaShop to the discount system
=> In Main HikaShop Configuration, Orders dropdown => Discounts.
=> Create a Discount, by clicking on New, then you can click on the Help button, to learn how to proceed.

If this isn't enough to help you, detailed with more elements your needs, to better help us, you have to help us.
Explain, the context, give a concrete example and how it work or the expecting result.

Regards