Use a layer node when you want to stack multiple effects or corrections on top of each other, blending them together in a specific order. Use a parallel node when you want to apply multiple effects or corrections independently and then combine their outputs equally at the end! It can be confusing so just play around with it A LOT!
bro bro your work is osm but this tutorial is not help ful because you did not explain in the right way your teaching styel like a kids please explain it more in detail how nodes works
