How to add a field in product and cart?

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Hi everybody and thanks for this grat forum
I have a trouble with a prestashop.
I have added a field in product.tpl, because I need customer enter a value in the product before add to cart (this value is the number of boxes in a pallet).
I know that its possible add a field with the tab Cuztomization in each product, but is too slow to make it in each product. I need to make in all products, and thats why i have done it.
I have try to put my field into the main form, but I cant to follow the path of this data. I think that It have to be possible to get with a $_REQUEST, but i can´t .

Well, the problem is that I need to put the value of this field in the cart, and, of course in the finally in the order.
So that i have two question really:
- How can I add a customized field to ALL MY PRODUCTS AT THE SAME TIME?
- How can I add a field to my product, cart and order?

Thanks !