I don’t see how the kernel version would be relevant. as all containers are based on images which are the same regardless of the kernel of your host operating system.
So if you still need help, please share more details about the issue including what you expected to see in the browser as we have no way to tell if the shared screenshot shows the right output or not.
But if you only meant to ask about where to put your custom config in the nginx container, that depends on what image you are using and you haven’t shared anything about that. Here is the description of the official docke rimage of nginx
https://hub.docker.com/_/nginx
It shows how to use it.