Kernel Source, modules, etc.

Hello All:

  I'm trying to follow the examples in Linux Device Drivers, 3rd
Edition. I'm at the simple first examples with the "hello world"

   My beagle board Xm running linux-2.6.32 does not have the source
code for the kernel. I cannot find a reference to a opkg module that
has the kernel source. Nor can I find one that includes enough .h
files and whatnot to allow me to compile a kernel module. FYI, I have
enough of a working system to code, compile and run gtk programs
written in C. So I have a working c complier, gtk, make etc ...

   I've also seen references to people cross compiling kernels, but
not real links. I fear in the no man land where those in the know
assume I know what I'm doing and the noobs would not know where to

   So .... how do you all compile and test your kernel modules? What
packages did you install to build up the system to support this ...

opkg install ..... .... .... ?

   Or is there a write up describing how to configure a work station
to support the cross compliation set up.

    If you can give any insights that'd be great, I'm sure other
people are having or will have the same issues. Any insights would be