Basically, an angular movement in the sticks of the transmitter ends up as an angular movement of one of the servos of the flying machine.
Both deflections are proportional (there is a feature named exponential which makes that proportion non-linear on purpose).
The steps are input deflection -> variable resistance (potentiometer) -> pulses per second of radio wave -> potentiometer of servo motor -> output deflection
That output deflection is used to deflect control surfaces.
For electrical power, the radio wave controls the amount of electricity (pulses) fed to the motor rather than the deflection of a servo.
Check this link for a better explanation:
http://www.rc-airplane-world.com/rad...trol-gear.html