Node.js express website accessible online

I have a website built using node.js and express in my iis webserver.

I can access the site by http://localhost:3000 and so can everyone else who are in the same domain when I put my files in /inetpub/wwwroot/ folder.

My question is, how do I make that website accessible from the internet/different domains?

My config.js file which is called from when I run app.js :

var config = {
local: {
    mode: 'local',
    port: 3000,
    mongo: {
        host: '127.0.0.1',
        port: 27017
    }
}

How would I modify my config file to reflect the changes I want? Thanks.