Creating an installation guide for Emscripten is going to be somewhat problematic. The WebAssembly technology changes frequently and the installation process for Emscripten may be different by the time you read this. I would recommend consulting the download and install instructions on the Emscripten website if you have any problems: https://emscripten.org/docs/getting_started/downloads.html.
You may also want to consult the Emscripten page on GitHub: https://github.com/emscripten-core/emsdk.
Google Groups has an Emscripten discussion forum where you may ask questions if you are having installation problems: https://groups.google.com/forum/?nomobile=true#!forum/emscripten-discuss.
You can also contact me on Twitter (@battagline), and I will do my best to help you: https://twitter.com/battagline.
