Hey I just wanted to put this out there for people that are just starting out like myself with arduino. Make sure that the cable that connects your board to your computer is plugged in all the way. Your able to plug it in only half way and your board will receive power but it won't be able to pass data. This can fool you since the board will light up appearing that the board and computer are communicating but they really aren't. The cable needs to be pressed in far enough that it almost snaps in. This will allow data to pass and not just power
Cheers!