i need to know how i can measure the transmitter power

hi all
i need to know how i can measure the transmitter output power
i mean the rf power in watt not theoretical
thanks

Use a power meter or a spectrum analyzer.
Mazz

thanks for reply
but it is hard to get spectrum analyzer here not avalible and what is power meter
i have voltmeter i can measure voltage and ampere only and i have
scope 20 mg can i use any one which i have?

You didn't tell either frequency or power range. If you don't have a RF power meter (it's exactly, what the name says), you should have at least a suitable dummy load. Then you can measure the power from dummy load temperature rise, calibrate it with a DC power supply.