Hi guys! I have a big problem I need to solve as soon as possible! I have an Arduino Mega 2560 and I'm trying to use Sparkfun's Mp3 Player Shield with it [https://www.sparkfun.com/products/10628?]. I have tried everything but I still can't manage to use it, there's is no sound at all comming out of the speaker. Can anyone post a step-by-step tutorial for me or explain it for me. Thanks!
That shield uses SPI, and the SPI pins are not at the same position on the Mega. See http://arduino.cc/forum/index.php/topic,125908.0.html and compare with http://arduino.cc/forum/index.php/topic,84190.0.html
You will need to connect the SPI pins on the Mega to the corresponding points on the shield. Or use it with an Arduino Uno.