If you are using LED lights on a lighting desk with basic faders you need to use one fader per LED control or DMX channel unless you know how to softpatch a desk that can have multiples DMX channels patched to one desk channel or fader.
The control of colour is not accurate as you are creating the colour visually by mixing the LED colours.
If you use a demo copy of LightFactory on a laptop, you can patch the LED fixture you are using into LightFactory, then select the LED in the Channel window, select the colour you want using Filters, then read the percentages of the colours on the fixture window and use those colours to set the lighting desk faders.