The "book" is likely RH Linux 9 for Dummies... or similar.
The "toy" version of Linux is called "Publishers Edition" beware!
He needs the kernel source headers for the linmodem modem (?) driver he's using, this does not come with the publishers edition - however, the gnu license requires that the source is available(!) so writing to the book publishers or the authors will help.
The problem with Publishers edition is when you upgrade from RHN - the rpm must check your current installation and assume your configuration is OK and 100% compatable. Then it just updates everything you already have in your kernel. In other words: if you start out with no headers, you ain't gonna get none via rpm.
I suspect that you can get the header files from RHN but I never did figure out how.
maddog reccommended getting the latest kernel tarball from www.kernel.org
(?) and customising - though RHN do not like you doing that. maddog also has a full Fedora distro with Fedors for Dummies on DVD which should not show these problems.