linux is the kernel
is the keepers of the linux kernel, as well as a few other apps, and quite a few person pages for people to put there apps online
anyways, read up on compiling kernels...
tho with your experience level (based on what you said) you might want to look into getting the kernel sources for your distro (that way they should be preconfigured, and you'll be less likely to get a unbootable system (trust me, first kernel compile is a real pain .. (not that it gets any easier, but the first time tends to be the time you make big mistakes))
anyways ... see if you have the kernel sources already
thats where they should be stored... /usr/src/linux should be a symlink into the current linux source tree you currently use
heres a guide to compiling if you need to compile