SOS for Kernel header files

Hi All
 
I am installing ncipher tool kit on my 7.3 (EE) Linux box. for building
the drivers, guide says folllowing

----------------------------- 
In order to build the driver with the supplied makefile, you must have
the correct headers installed for the kernel that you are running. They
must be headers for the same version of the kernel and contain the
kernel configuration options with which your kernel was built. The
makefile looks by default in /lib/modules/current kernel
version/build/include for the kernel headers.

If the kernel headers are located in a different directory, change the
variable LINUX_HDRS in the makefile to point to the correct location.
Historically, the headers have resided in /usr/src/linux/include.
-----------------------------

But I I do not have these files anywhere!!!.. From where I can get these
files?? From which CD?? From which site?


Regds
 
Ajay Bansal
Infosys Technologies Ltd
Mohali
91-172-257194