My assumptions: You have prior experience of Web framework like Ruby on Rails, Django, Phoenix, etc. Please refer to this React.js style guide for community comprehensible source code.
Hey, its not mandatory to use NPM to build applications with ReactJs; but, it will be alot easier to build, maintain, share codes using NPM. Firstly you should have NodeJs installed in your development machine.
Installation for Development Environment
$ sudo apt-get install nodejs # try $ node -v # v4.2.6 # if its says
command not found: nodethen try
$ nodejs# If it shows up, it means due no some name conflicts # the name/command node is already taken by some binary. # So, its get it back.
$ sudo update-alternatives --install /usr/bin/node node /usr/bin/nodejs 10