Keep in mind that blending images works best when they are of the same color scheme. Make a new document (CTRL + N) and drag both your images to the same document. Now, this is an OPTIONAL step - use the Rectangular Marquee tool, set to Feather at 4 px, and delete the edges of one of the images.

Sometimes you don't need to do that, it depends on the borders of the image you're blending. For the 2nd layer, you need to Add Layer Mask. Go to your Layers window, and choose this icon:

Now use the Gradient Tool, and make sure it's set to Black to Transparent.

Drag lightly between the two images until you get something that looks nice. Smaller drags work best. This is my result:[Screenshot]