Setting up a server via arduino YUN

Hi everybody,

I am a new user of the arduino Yun and I was following this guide ( Accessing Your YUN Worldwide - Arduino Yún - Arduino Forum ) in order to set up a server. I managed to follow the first and second step (I ignored the third one for various reasons, main one because my router didn't allow me to book an IP) and then I read the fourth one and I got completely crazy trying to figure out where to add the sketches.

I would be so grteful if any of you could point me to a newer guide or directly tell me what to do.

Thank you!