This is so simple, I swear y’all. So, first things first.
1) Open a new file, and the two pictures you’d like to blend. Drag them both in the new file you open at first:
2) Pick the eraser tool, and pick this brush:
3)Now start erasing the unwanted parts from the top layer, until you have something like this:
4) Use a PSD or add your own coloring/textures and taadaa! you’re ready to go.
hope that was helpful!