To make a Gradient Mask
* Click on Chalet layer to make it active.
* Open Layer palette, and click on Layer mask symbol (dotted circle) to add a layer mask.
* Go to Tool palette, and select Graduation Tool, by Alt+Clicking on Paint Bucket.
* In Bar at top of page select Linear gradient.
* Set Foreground/Background colours to Black/White.
* Make Layer mask active, by clicking it in the layer palette.
* Now drag the Gradient Tool cursor from left to right on your picture to get a gradient mask (or right to left if needed).
* Experiment with where you start and stop the drag to get the blend transition you want.
I got this from this forum:
http://www.retouchpro.com/forums/photo- ... ption.html