Download Local Server and unzip it. Install and start as any other Node.js component (see Reference for details). After this operation, your terminal should show something similar to this:

To check if everything works as expected, you can set up one of example devices from Examples section. On screenshot below, Range Converter example was used (can be started on machine that is running Local Server without additional setup)

If you can see the above in your browser, means you are ready to go :). Explore Reference section and other Examples to create your own IoT system that fits your needs and imagination.