Linux Lite Kernel

[gold_finger]

Your sources list probably needs to be refreshed first after initially installing the system.  If you run sudo apt-get update before running those commands, it should then work.  However, if you just did a fresh install, run the regular "Install Updates" (Menu -> Install Updates) to install all initial updates first.  Then install the new kernel afterwards.  (If you run "Install Updates", that will automatically update the sources list so you won't need to run sudo apt-get update before the kernel upgrade in that case.)