Basic Question 3DR 900 and Pixhawk communication

Hello all,
I am new to this forum and to the Ardupilot and RC communities in general. I have a very basic question that I think the documentation expects the community to already know. When using a ground control station software such as APM Planner 2.0 or Mission Planner, how exactly does that information get from the computer to your servos and motor controllers? I am under the impression that the information is transmitted to the Pixhawk via the two 3DR 900 radios. After the information is received by the Pixhawk controller must it then talk to an external RC receiver before the Pixhawk can control the motor controllers and servos? I am sorry in advance for being such a noob on this topic!!! I guess I am mainly wondering if it is possible to use the Pixhawk controller itself as an RC controller.
Thanks a lot in advance and I hope I am not being too much of a nuisance!

@JMA89089,
The telemetry radios are strictly for monitoring and changing the Pixhawk full parameter list with a CGS such as the Mission Planner.
You use your transmitter to control the rover manually through the Pixhawk that is attached to your steering servo and ESC.
Please read the wiki: http://rover.ardupilot.com/wiki/gettit/
Regards,
TCIII AVD

I have read that wiki page already. I may have stated my question wrong, can I run the autopilot without having an RC controller/receiver connected to the Pixhawk?

@JMA89089,
Yes it can be done through the Mission Planner over the Telemetry link using a joystick plugged into the host PC. However I do not recommend it unless you have a lot of experience.
Here is the Wiki section on using joysticks/game pads http://copter.ardupilot.com/wiki/common-optional-hardware/flying-with-a-joystickgamepad-instead-of-rc-controller/
Regards,
TCIII AVD