I want to use my nexus s to tap on the nfc shield, and it will send id of student to the shield. Next data will send to computer to attendance check for student by ethernet shield and record it to the server ?
Anyone can help me to do this ??
now i have nfc shield from seeedstudio NFC Shield | Seeed Studio Wiki
I don't know how to use nexus s to keep id and send by using NFC.
Thank You 
Those two shields will not work together without some "pin bending" and rewiring/recoding. Both use digital pin10 for the SPI Slave Select pin.
Can i change pin to work together ??
WARNING! I will try about anything, so you are on your own if you try this!
The nfc shield must be the top shield.
Bend digital pin 10 on the nfc shield so it does not connect to the ethernet shield.
Install a jumper wire on the nfc shield from digital pin10 to digital pin9.
Then in the nfc "driver" code, change the SS to pin 9 instead of 10
#define SS 9
Add: I would also go through that nfc code and insure it manages that SS pin correctly. It should set pin 9 LOW, then do any SPI read/write, then set pin 9 HIGH before returning.
Interesting,
I was thinking to try the same with a nanode and NFC shield or NFC breakout.
I think ~~SS is also pin 10 on these.~~correction: SS on pin 8 (for Ethernet chip)
SS on Pin 10 for Optional wireless board (or fitted in nanodeRF).
Don't have the NFC shield to hand today though.
Let us know how it went?
I will update when I can.
cheers,
Jim