I want to fade a layer from 100% opaque to 0% opaque and I was wondering if there's any way to do this, maybe with some kind of opacity gradient or something?
what what what?! there's more than one way to do things in photoshop!
i like fatbat's solution better. especially if you have to see things below the layer. there's a few considerations to make (are you using a layer mask already - not as good of a solution). you could always make an overlay or something too.
You ought to buy a book. I would recommend something on Lynda or Peachpit. This is really basic stuff and the sooner you get the hang of it the better. Read as much as you can!