[Gimp-user] Q: How to apply transparent gradient to image?

[D. R. Evans]

I have a simple PNG image, and I'd like to change the top half so that at
the very top the image is completely transparent, with the opacity
increasing linearly so that halfway down the image (and all the way to the
bottom) the image has 100% opacity.

I've messed with layers and gradients until I want to scream -- I can't
find the trick that allows me to do this. (It seems like it should be dead
easy.)

Could someone please point me toward something that describes how to do this?