This is a checklist I've used for installing River4 on a fresh Ubuntu v14.04 server.
sudo apt-get update sudo apt-get install nodejs sudo apt-get install npm sudo apt-get install nodejs-legacy
We also install npm, a requirement to run Node apps.
nodejs-legacy makes it possible to run apps by saying node app.js instead of having to use nodejs, an oddity of Ubuntu.
sudo npm install forever -g
There are lots of ways to get apps to launch in the background, I like forever because it keeps the app running even if it crashes. River4, of course, never crashes (heh) but you never really know.
sudo apt-get install git
I like to install git, because it makes it easy to install River4 from GitHub.
git clone https://github.com/scripting/river4.git
That should create a directory containing River4 at /home/ubuntu/river4
To run it, follow the instructions on the River4 howto.