¿How to add field for customize product?

I need create a produt that can be customizable, espcificly a card with a message of congratulations.

this propduct have 3 field custom that my cliente will input in the product view:




But i dont know hou to implement this funtionality in my store.

I tryed with https://github.com/vtex-apps/product-customizer but my store dont have VTEXIO then i cant use apps.

thanks for your help