If you want to develop for ARM chipsets, first step is to install the ARM compiler into a set location. This toolchain is used by dozens of different chip companies so its always handy to have

Go to https://launchpad.net/gcc-arm-embedded/ to download the toolchain for your operating system

You may need a particular version, for example https://launchpad.net/gcc-arm-embedded/4.8/4.8-2014-q1-update for what you're doing, check your chipset or Makefiles for any hints

Download & run the installer

However, when it comes time to install into a folder...

I like to install into C:\ARM\4.8_2014q1 (or whatever the version you're using is) which doesn't have odd characters or spaces - sometimes makefiles choke on spaces or the (x86) in the default path.

And add the path to the environment variable

Once installed, make sure you've got the files installed in the right place

From the command line you will now have the arm-none-eabi tools available.

Note that you do not get other tools like make! You can get those by installing the AVR toolchain, though