No flickering.
So you know how the white LED has a resistor? My dimmer is in series with that resistor, so it just adds more resistance (between nearly 0 ohms and 10k ohms). I use the terms dimmer, knob, and potentiometer interchangeably.
The rotary potentiometer in the diagram is only one type; slide potentiometers are the same wiring but with pins in different places. If you have a potentiometer and multimeter on hand, you can find out what each pin does by measuring how the resistance changes (or doesn’t) while moving the knob.
If you look up tutorials for potentiometers, it may be confusing at first since you will usually see 3 wires going to a potentiometer, but in this case you should only use two wires.
Let me know if you want me to explain more.