How to apply glow effect for fill path in a dial? [newbie need help]

Hi all, as title mentioned, I am trying to add a glow effect onto a rotary dial I created, the fill color is a blue and I would love to have a glow effect as I move the knob.
I am very new to JUCE and coding but have been building my own designs, currently learning and practicing more with the LookAndFeel class, but I am having trouble adding a simple glow effect.
Any help is appreciated thank you!