build is missing for compiling kernel module

this is my first time trying to create a kernel module, apparently after creating a module I need to follow these steps to compile it:

echo "obj-m := Hello.c"> Makefilemake -C /lib/modules/`uname -r`/build M=$PWD modules

here's my problem, there is no "build" in "/lib/modules/uname -r/" directory!

what am I missing here?