Just continue on - link more sources (switches, knobs, sliders) to more channels in the "Mixer" like the first 4 you already have.
You can do up to 24 channels for in flight or in game controls, although 12 is usually sufficient. It doesn't matter much which source is using which channel, so gear (for example) could be on ch 5 or ch 22 or some other. When configuring the Controller in RF, you would then "map" the control to the function. So for gear, just flip the switch you want to use for gear, and RF will associate the channel you used with that function from then on.
A couple FYI's - if using the Spektrum or other dongle for wireless, you can only use the first 8 channels. To use more, you have to use a usb cord.
Make sure that channels 5 and 6 are linked to a control with a center position (3 pos switch, slider, knob). Windows doesn't like having a 2 pos switch on those, and it leads to problems in the RF controller configuration.
Do you still need the driver? What for?