Etherpad is a really-real time collaborative editor. Here is how I installed it and use it now.
a) clone the repo :
git clone https://github.com/ether/etherpad-lite.git
b) enter the directory
c) run the run.sh
d) access your Etherpad at http://0.0.0.0:9001/ in your browser
e) Create a Pad by giving it a name ‘new_pad’
f) share it with the address http://0.0.0.0:9001/p/new_pad