Trouble signing kernel modules for Virtualbox

I recently installed VirtualBox, and I am having an extraordinarily hard time signing the kernel modules for Secure Boot. I have already generated a RSA key pair and enrolled my .der file into the MOK manager. How do I go through with actually signing the modules themselves, though? Do I have to cd to a specific directory while signing the modules? And where are the modules even located?

Perhaps you should try GNOME Boxes or Virt-Manager.
They rely on libvirt+KVM/QEMU and require no extra modules.

Andreas Mueller provided instructions to sign a module at Virtualbox vboxdrv kernel module not loaded. The instructions are prescriptive so they provide all the steps you need to perform. It is a high quality post.