Open both images in Photoshop
Select the person with the Quick Selection Tool, Pen Tool, or Select Subject
Refine the selection with Select and Mask
Copy the selected person to a new layer
Drag or paste the person into the target picture
Use Free Transform to resize, rotate, and position the person
Match the perspective and scale to the background
Add a layer mask to clean up edges
Adjust brightness, contrast, color balance, and saturation to match the scene
Add shadows under or around the person if needed
Blur or sharpen the person to match the background focus
Blend the edges with a soft brush on the mask
Check for mismatched lighting or color and correct it
Save the file as a PSD and export the final image