It’s pretty simple. You are probably right, the official documentation at http://docs.openhab.org/addons/io/hueemulation/readme.html is a little bit shorthanded. 
In the thread about the Hue emulation binding you can find a short tutorial from @Toneus:
Other than that, and if you are german, there is another tutorial (combined with a KNX connection, but can be used for general setup also):
http://onesmarthome.de/smart-home-openhab2-sprachsteuerung-konfiguration/
The only issue I had (I connected my Echo some days ago): Alexa couldn’t find new items. I found someone who said that I had to disconnect my hue bridge during the Alexa discovery. Done that and then it worked flawlessly! So if you are also using HUE, you should consider this. As the binding uses a HUE emulation, maybe those two don’t like each other?! After the discovery, the hue bridge can be reconnected of course.