How to add the discount 20% to the product, so it's shown that it is on sale and a new price?

[ColDuMarine]

Where to enter the amount of the discount to the product card so it's shown that it is not a regular price but a special price 20% and a new price is shown 

[nat_not]

@ColDuMarine Such a indication is available within Strefa Okazji. Click here for details.