linux kernel compilation

hi all

i am new to the linux kernel code.I am trying to compile the linux kernel downloaded from the kernel.org site, but its giving error saying GAS is not installed.I dint get GAS on the net.
Do i need to separately install it.can somebody tell me the way it is installed and in which directory?

second question:
I have linux fedora core running at my home PC, i am supposed to get the source code in the /usr/src or /lib/modules directory but I couldnt find it there.

I want to start kernel module programming and device driver development.Can somebody please suggest me the best site where everything from the beginning is available.

Thanks
Rahul