Add an input in Wordpress

I need advice to add an input to increase the quantity of a product in Wordprees.
The page uses WooCommerce and Porto theme
And I want only one price to appear, I use the porto theme for this part but two prices appear

My page is: https://mayorlei.com/

And I want it to have this style of input and add to cart button: https://denovedad.com/tienda.html

The advice can be by message