SQL custom function to calculate price of product after discount applied to it

I need help to write a Custom function in order to calculate Price of Product post the discount is applied.

I am fresh to SQL, hence went through few articles.

Came up with Scalar function and in order to execute the above result wrote the below code.

But no Success 🙁

CREATE FUNCTION CalcPrice
(
@PriceOrg decimal(10,2),
@PrdPrice decimal(10,2)
)
RETURNS decimal (10, 2)
AS
BEGIN
DECLARE SELECT(@PriceOrg - @PrdPrice)
END

Save the above function and call the function as below

SELECT dbo.CalcPrice();

But nothing works for me.

Below Image for the Product table

Products Table