Blend One Photo with Another?

Start by putting each image on its own separate layer, and make sure they overlap (after all, if they don’t touch, they can’t blend). Click on the top image layer, then click on the Add Layer Mask icon at the bottom of the Layers panel. Nothing happens visually at this point (except that it adds a mask to the right of that layer in the Layers panel). The next step is where we blend. Get the Gradient tool (G) from the Toolbox, choose Foreground to Transparent from the Gradient Picker in the Options Bar, and click on the Linear Gradient icon next to the Picker. Press the letter X to set your Foreground color to black, and then click-and-drag the tool either from left to right or top to bottom (or both, if you need to). Where you start clicking-and-dragging is where the image on top will appear transparent and, as you drag, the image will blend into the background image (which is what it’s doing, by the way). If you don’t like how it blends at first try, press Command-Z (PC: Ctrl-Z) to Undo and just click-and-drag again. If you don’t like the results at all, go to the Layers panel, click on the layer mask’s thumbnail, to the right of your layer’s thumbnail, and drag it onto the Trash icon at the bottom of the Layers panel.