_BV() Bit manipulation function
AVR Libc Reference Manual
http://www.nongnu.org/avr-libc/user-manual/group__avr__sfr.html
OCR2A & OCR2B only change the PWM duty cycle
http://playground.arduino.cc/Main/TimerPWMCheatsheet
Check the datasheet page 94 for more info on PWM
http://arduino-info.wikispaces.com/Arduino-PWM-Frequency