_inc_node-red_install

First, install Node.js. There a number of options. On my Windows machine, it just means downloading an installer and clicking through the default installation options.

You can verify Node.js is installed by entering the following command (npm is the "node package manager", part of Node.js)

C:\Users\twatteyne>npm --version
2.15.9

You install Node-RED through npm:

npm install -g --unsafe-perm node-red

Finally, you can start Node-RED:

C:\Users\twatteyne>node-red

Welcome to Node-RED
===================

1 Sep 15:02:04 - [info] Node-RED version: v0.14.6
1 Sep 15:02:04 - [info] Node.js  version: v4.5.0
1 Sep 15:02:04 - [info] Windows_NT 6.1.7601 x64 LE
1 Sep 15:02:04 - [info] Loading palette nodes
1 Sep 15:02:05 - [warn] ------------------------------------------------------
1 Sep 15:02:05 - [warn] [rpi-gpio] Info : Ignoring Raspberry Pi specific node
1 Sep 15:02:05 - [warn] [tail] Not currently supported on Windows.
1 Sep 15:02:05 - [warn] ------------------------------------------------------
1 Sep 15:02:05 - [info] Settings file  : C:\Users\twatteyne\AppData\Roaming\npm\
node_modules\node-red\settings.js
1 Sep 15:02:05 - [info] User directory : \Users\twatteyne\.node-red
1 Sep 15:02:05 - [info] Flows file     : \Users\twatteyne\.node-red\flows_HDC_SW
01.json
1 Sep 15:02:05 - [info] Creating new flow file
1 Sep 15:02:05 - [info] Starting flows
1 Sep 15:02:05 - [info] Started flows
1 Sep 15:02:05 - [info] Server now running at http://127.0.0.1:1880/

Point your browser to http://localhost:1880/ to see the Node-RED web interface:
Geeky details

As you can see from the URL above, the Node-RED application starts a web server which listens on port 1880.

Following the excellent Getting Started guide if you want to learn more about Node-RED.