Take a look at the sketch in the Arduino IDE called SimpleWebServerWiFi, go to File/Examples/WiFi/SimpleWebServerWiFi ...this will give you an idea on how to start.
If you want to use Node, there is an example in their website that will be useful for you. Node.js
About the app for your smartphone it will depend on the OS you are going to use.
For example with Android:
Ok, If I am not wrong, to fullfil what I want to do,
For example, firstly I would have my nodejs program for Intel Edison to blink a led or read a GPIO input, and I have to send that ouput signal to a webserver via WiFi. Then I have to do an HTML5 web app that show to the user a screen with an icon of a led that changes the state in real time via query I suppose to.
It is that rigth?
Thaks in advance.