using layermask

This tutorial will help you to make a simple collage of two pictures. First you'll want to place the pictures on different layers as shown at the left. Not very collagish, huh? That's, why we'll apply a layermask to the upper picture in the next step.

Use Layer -> Add Layer Mask -> Reveal All after selecting the upper layer to get a layermask. Nothing happened? Well, now for the tricky part: On your layerwindow you see a weird white square next to the current layer, huh? When you click it and use black or grey in your working area, you'll see your actual picture fade out at these parts. Although you could use almost every tool to fade this pic, we'll use a black-to-white-gradient for this tutorial. Press "D" to select black as your foreground- and white as your backgroundcolor, choose the gradient-tool and drag it from right to the left end of your picture-to-fade. Have a look at the blue arrow if it doesn't work at the first time.

This is the final picture. As you can see the upper picture fades out nicely to the other one, creating a smooth look. Try other tools like the brush and experiment with more shades of grey to get other results. If you made a mistake, just use white to make the picture visible again.