GNU/Linux Debian Installing New Kernel Offline Guide
You Are Welcome! The Tutorial shows you Step-by-Step How to Download and Install Offline a New Kernel without Internet in Debian GNU/Linux.
Most noteworthy: to achieve this Setup you simply need any Online Computer with a Browser and a USB Stick to Copy the downloaded Packages.
But if you dispose of an Android Mobile Phone with Internet Acces, then an Easier Solution should be of using it! See: Internet Connection USB Tethering Guide.
Finally, the Guide include also instructions about How to Install Linux Kernel Headers Offline for Debian.