How can I offer recipe discounts in my online cooking business?

If I am set up a business on Shopify where customers can send you recipes and pay you based on how the dish looks and tastes, how do give my customers a discount for when they are submitting their recipes files on a Recipe Request Form while Adding fields for recipe name, ingredients, instructions, and any other relevant details. And if your wondering what my business is:I will be making the food and giving them to the customers, and before I get payed I just need them to the dishes will be made for both pickup and delivery but I want them to me any recipe they can think of, from any country, appetizer, entrée, or dessert, I would be happy to make any of them. But I can only do one at a time and sometimes multitasking, and even though I’m only a cook,not a chef I’m still willing to take a chance. And yes the recipe will be displayed on my website.

Should the discount code be in numbers or letters? and what type of app should I use to create a discount code specifically for recipe submissions then let the recipe request form be displayed on my website?

How is the bold discount app useful for my business?