Linux Kernel Header File Location

I am running a linux OS.

I want to know the locations of the header files.

I have tried the following :-

cd /lib/modules/$(uname -r)

But there are only two .ko files inside it. I expected results which include folders like build(which contains the include folder, which inturn consists of the header files)

I have even tried doing this :-

sudo apt-get install linux-kernel-($uname -r)

Output

E: Unable to locate package linux-kernel-3.8.13-OpenNetworkLinux-e500mc-1.5E: Couldn't find any package by regex 'linux-kernel-3.8.13-OpenNetworkLinux-e500mc-1.5'