Dear All,
How i can build my PWM generation using all the THREE Timers in ATMEGA328P. And in that program i need to use Registers or similar header file available(if any) to use and generate PWM.
Take a look at chapter 15 through 18 of the '328p datasheet - that explains in excruciating detail how the timers work and how to generate PWM with them.
The compiler already knows the register names - you can write to them like they were variables.
You can also take a look at how Tone() is done in the source for the Arduino core, and how they do PWM with analogWrite() (note also the init() function).
The Arduino IDE automatically includes code from wiring.c (the init() function) which you can look at to see how to setup the three timers. With those settings the AnalogWrite() function in wiring_analog.c is able to connect the Output Compare (e.g. OC2A) to the pin (e.g. PB3 at pin 11) and the pinMode() function in wiring_digital.c is also needed to set the data direction bits (e.g. pin 11 uses PB3 bit in DDRB).