I don't know if there's any tutorials, but I know how to do it. First, take your text or image layer, duplicate it and flip it horizontally. If you don't know how to create a layer mask, go to Layer -> Mask -> Add layer mask. Do this on the flipped text layer. A box should come up, just click add. Go to the gradient dialogue and change it from 'FG to BG' to FG to Transparent. Then just click and drag to make it fade out. Final product.