Hey there, the process is extremely simple. Just do the following:
- Go to your Shopify admin > Discounts > Create discount
- From the Select discount type menu, choose Amount off products or Amount off orders. Under Method, make sure Discount code is selected.
- In the Discount code section, enter a unique name for the discount code, such as the model’s name or handle.
- In the Value section, choose either Percentage or Fixed amount and enter the discount value.
- Set a minimum purchase requirement or limit the discount to specific products or collections (this is optional).
- Under Applies to, select whether the discount applies to specific products, collections, or the entire order.
- Finally, save the discount code.
You can read more on it here - https://help.shopify.com/en/manual/discounts/discounts-faq
Here’s Shopify’s documentation.
For the monetary aspect, you might need to install an app. You can find some on the Shopify app store.