What I've done in the past is basically (For Fireflies):
Pick Gradient tool
Pick the one that goes from White to transparent
Make it a Radial Gradient
Edit the Gradient to the colors you want White to Yellow to Transparent, or add a red/orange at the end and then create small spots with it.
Go to Blending option and play with the Size/Spread/Opacity
For the magic sparkles You can pick a brush that looks like small splatters. Pick a while or yellow color and then adjust outer glow in Blending options.
Hope that helps.