Show notification when selecting country x when adding address in Prestashop 1.7

[Albatrosss]

I'm using Prestashop 1.7.6.8. When adding an address for members or those who want to place an order without being a member, for example, I want to show a warning on the screen if they choose Germany. Something like an information note. How can I do that? I'm new to Prestashop. Which file do I need to make changes? Thanks.

[PrestaServicePro]

Hello, 
Could you say where exactly you want to show the warning message?

I mean exact page of the warning message.