npm is a package manager.
You will use it to download packages and to update the ones you are already using.
This handsome npm is installed with Node.js, so you have to install it.
Now you can check if everything is ok opening a console and:
node -v
npm -v
It should show you the installed version of the two bad boys.
Now you can start to plan your Death Star, but before you also can update your npm to the latest version.