Not sure exactly what you are asking. The collective is used to change the angle of the main blades and is separate to the throttle which controls the speed of the blades. Helicopters have beginner mode or sometimes called normal mode where the throttle and collective are both controlled with the same input channel. This limits what the helicopter can do so they have other modes where the throttle is fixed, this allows the helicopter to use negative as well as positive collective and be able to fly inverted. I hope that answers you question.
I am using the ws2000, On my TX16S I have three flight modes #1 normal throttle 0-100% pitch -2%-100% #2 IDLE UP 1 throttle 70% pitch -100%-+100%, INDLE UP 2 throttle 78% pitch -100%-+100%. How do I map the channels?
You map channels using the Controller Profile in RealFlight.
It's important to note that RealFlight is designed to be controlled by a transmitter setup for a basic 4-channel airplane. RealFlight applies a throttle curve and a pitch curve on helis within the program itself. Those settings are preset in the virtual model using the Aircraft Editor. RealFlight just expects normal throttle movement from 0% to 100% and no pitch channel input.
For more info about mapping channels, see this writeup.