When I started with PhotoShop , I remember that also cost me. Something that seems so simple annoying that gives it simple. That’s why , although I recommend to keep trying to achieve the gradient as explained in this tutorial , I propose an alternative to achieve the same effect. And it is a cheaper alternative , is a tool that henceforth we will use very often. The same is layer mask. Here :
Step 1: Open a document and import to merge the two pictures . This point I skipped to explain assuming that is already clear. I have the picture here and in the layer 1 vertical and horizontal picture in layer 2 (no need to be vertical and horizontal , but I follow the example of the previous tutorial ).

Step 2: In the picture below, see the layer panel . In it I marked where the toolLayer Mask“With a red circle. Being in the layer 2 (above) , you click on “Layer Mask“And the panel will show a white box next to the image. Let us see if the image:

Basically what this tool is to hide everything painted black and show everything painted white.
Step 3: Once done, press the ” D “to reset the default colors ( black and white front to the background .) Select the Brush tool from the Tools panel and give it a value, such as the circle you see in the picture below ( depends on the resolution of the photographs that we are using , that’s why I do not give values.)

What we do is paint the bottom edge of the picture above . We will see that instead of appearing black, will fade the image, what we’re painting . In this way we can achieve a merger between the two images. Remember that hardness Brush ( when selecting the size is also this property of the Brush ) must be in zero, to have a blur .
To reach a mistake and leave invisible party wanted to see , just enough to rotate the colors ( black and white face in the background) and white paint section we want to display. Remember : The invisible black , white visible.

Simple , no?
Link | Herramienta Máscara de Capa