Add a required field for gender on registration form

[BenjShop]

I manage a site via Prestashop, I've been trying for several days to enter a condition for my code but I can't, that's why I'm asking for your help :)

It is to put "required" for the choice of gender on my site "man" or "woman" to make the selection obligatory. 

When I replay this: 'required' => true

I get an error when I validate the form like this: error

Can you help me?