using the automatic to manual swich on 1990 735il transmission

Can anyone help me, I got a 1990 bmw 735il and I'd like to know how to properly switch from automatic to manual on my transmission it has the switch A to M but I don't know if the car has to be turned off or on, cause I don't want to do it the wrong way

It is shift of the fly, so you can switch it from automatic to manual at any time. It won't harm the transmission or the programming because that is what it was designed to do.

Hope this helps...