Adafruit RFID PN532 + Ethernet Shield + Webservice

I'm sorry but I'm a total newbie about Arduino.
I want to get an ID stored in a RFID card with an Adafruit PN532 and to send the value through Ethernet via an Web Service.

First do you think it's really possible (please tell me it is) and have you got any example about working with an Web Service ? (I think it will be the hardest part)

I tried to combine this (Adafruit_NFCShield_I2C/readMifare.pde at master · adafruit/Adafruit_NFCShield_I2C · GitHub) and that (thingspeak-arduino-examples/Arduino_to_ThingTweet.ino at master · nothans/thingspeak-arduino-examples · GitHub) and I can't make it work unfortunately (I don't know anything about this kind of programmation)

Thanks for your help!