First you'll need to make sure your system has a c++ compiler. For OSX, XCode will work, for Ubuntu, the build-essential package works. You'll also need `git` if you want to track HEAD.
To install create a folder somewhere in your filesystem with the nvm.sh file inside it. I put mine in a folder called `.nvm`.
To install create a folder somewhere in your filesystem with the "`nvm.sh`" file inside it. I put mine in a folder called "`.nvm`".
Or if you have `git` installed, then just clone it: