*Where do I plug the power cord in?
*What goes into the "B/CH4" slot?
RC equipment has been designed to be fool proof, so if you plug it in the wrong way nothing will fry. The B stands for battery. The reason why it also allows CH4 (channel 4) is if you use a Y harness
you can add a battery and a servo in the same slot in any slot.
The C-25 controller is basically an H-bridge
that operates by an RC signal. Plug one wire into the reciever, two onto the battery leads, and two on the motor leads - and wallah its controllable by your transmitter. I was thinking about getting one of those speed controllers for myself just a few days ago . . . I think Ill add them to the remote control robot tutorial now . . .
The transmitter manual that Militoy gave you should help you with your last question.