Humm, don't you like those questions that arn't anything more than a few words lucky enough to bearely qualify to be a sentence, but not even enough to qualify as a question (was that a question)?
No offence, but what kind of power meter (electrical, RF, ...)? What do you whish to know about using an AVR to do it (interface, AVR programing, ...)?
You would need some sort of sensor, that convert power to a voltage. Then, an ADC (for which some AVR does have). And, finally, a user output (something to display the result or to communicate it to the user, like a LCD display, a LED display, a serial port...).
You can separate your project in 3, and really learn about each sections independently.
- Analog part, which are the converter (the sensor). Which convert power to an analog value, let's say, from 0V to the limit of the ADC input.
- Digital MCU part, which start at the ADC, convert the voltage to a digital value, and sent it to the output
- Output. For serial port, simply have a serial comm module. For LED, you could have some circuitry that take some AVR IO pins convert to 7-segment display. For character LCD display, there are modules easy to use, it's just a matter of using a small communication library. There are some already done for AVR.
Big Boy