I have raspberry-pi 2 And i want to Build tails OS to work on it I downloaded the source code and installed cmake and gcc-arm-linux-gnueabi but i have no idea how to do that. I searched online but i found myself stuck with lot of links talking about thing called cross-compilation but i don't know what is they talking about!? Any help?
Tails OS does no run on the Pi. Per the Tails OS FAQ:
Does Tails work on ARM architecture, Raspberry Pi, or tablets? For the moment, Tails is only available on the x86 and x86_64 architectures. The Raspberry Pi and many tablets are based on the ARM architecture. Tails does not work on the ARM architecture so far. Look for a tablet with an AMD or Intel processor. Try to verify its compatibility with Debian beforehand, for example make sure that the Wi-Fi interface is supported.
cross compilation means compiling on a different machine or architecture than the code will run on. For example compiling tails on your PC for use on your Pi.