controlling color leds with a potentiometer?

[AwesomePixelMan]

Hi there!

I am currently working on a small dc poweradapter that outputs 16A on variable voltage between 1.4V and 1.8V. The main component is a TI step-down (PTV12020LAH) with a max. of 16A and a Vadjust pin that measures resistance to ground to set the voltage. That's where the poti comes in; it's value is given by the step-down, namely 10k. All of this is going to fit inside a small cnc'd woodden box, featuring a band of light (3mm plexi with leds to light the sides) that should change colour based on the setting of the poti/ variable resistor . If it's  value is zero, and the voltage is low, green leds should be lit, and when the resistance is set high, likewhise the voltage, red leds light up. The change in color in between should be gradual and when power is applied the leds should fade on in about a second and fade out when the unit is turned off. I have a swich that grounds a pin on the buck module as a soft on/off. I currently have installed some green leds, but they don't fade in.

The device is powered by a regular 12V dc wall wart.

I do not have too much knowledge yet, in fact, this is my first ever project! My equipment isn't too good either, so smd stuff is a bit tricky to do for example.

How can I cheaply and easily achieve this?

Here is a picture: