QUESTION: How do you gradient something into transparency for example this image:
I'm assuming you mean the little flares in the background?
My guess is you'd have to use some sort of mask. I am not positive though. I'm just guessing as I'm the type that figures it out while it's in front of me, and I'm not in front of my Mac or photoshop.
What I'd try is going into quick mask mode, then grab the ellipse gradient tool, drag out a circle by pressing shift while dragging, then with the spot in the middle added, exit quick mask mode. You might have to invert the selection depending on what you want to do. Then from there you can add effects, filters, whatever and it will slowly fade out. Mess around with that technique. I'm sure you can do it somehow that way.