in a terminal gives an output saying 3.13.0-37-generic, but I am trying to upgrade the kernel to 3.16, and indeed I have ran
sudo aptitude safe-upgrade
which installed linux-headers-3.16.0-34 (3.16.0-34.45), but running
uname -r doesn't show that. I am doing all this because it seems to me that virtualbox dkms can't find a kernel source for 3.13.