Matrix style product ordering

I come from the uniform industry, where i have put up web stores for customers. I know very little about actual coding for this, so it is out of my ability…
In previous store environments (from other web companies), customers have been able to log on and order multiple quantities of a product, in multiple sizes at one time. Not picking 10 size small, added to cart, then going back and adding 15 size medium… They just fill in like a grid. See attached picture. Anyone know how to code that for Wix?