Reply to Mapping Help

I have a small easy problem for a mapping master to help me out but I am HORRIBLE with this mapping stuff. It's to confusing for me haha.

Basically what I need to do is create a gain mapping to a key and also when I press/hold shift and turn a knob on my Twitch it will change the selection of the FX.

If anyone has some spare time to help me out maybe msg me of post here??