Provided we are talking a stick transmitter and not a wheel tx
on four channel Transmitter using mode 2, (throttle on left stick) mode 1 uses throttle stick on right.
"A Mode II RC transmitter controls the aileron (roll) and elevator (pitch) with the right hand, while the rudder (yaw) and throttle are controlled by the pilot's left hand."
left stick usually controls throttle (ch3) and ch4 anything else that requires a proportional input/output
right stick usually rudder (ch1) and ch2 again a proprtional input/output.
on a six and upwards transmitter there are switches that control anything you need to (I have a ten channel transmitter)
If you wish to switch on any lights and devices they would need to be switched from the reciever via a RC switch, turnigy do them, including a 7 channel switcher, or you can find them on e-bay, around £12 - £21.
If you want to switch via a stick, you would need a latching switch, (one that switches on at a given position of the stick input, latches on and switches off again when the same stick is positioned to the same position again)