Patching & Recompiling Kernel

[Can Sar]

Hi,

I emailed the list earlier, about a problem I had, but I tracked it 
down, and can formulate it as a simple question now. I need to change 1 
or 2 lines in the Linux Kernel, and then recompile it. Where can I find 
the sources in Ubuntu (do I have to install them) and is there some 
place I can go for information on how to recompile it. I found a 
general guide for Debian (http://www.desktop-linux.net/debkernel.htm) 
but I'm not sure if it applies.

Thank you for your help,
Can Sar