This Library is deprecated. Please check here for the new library:
https://github.com/DFRobot/DFRobotDFPlayerMini
DFPlayer-Mini-mp3
Install instructions:
Download file
decompress
copy inside folder to your Arduino library folder
restart your Arduino IDE
Check the wiki for more information:
http://www.dfrobot.com/wiki/index.php/DFPlayer_Mini_SKU:DFR0299