Open Photoshop
Click File
Click Open to add a picture as a new file
Select the image
Click Open
Click File
Click Place Embedded to add a picture into an existing document
Select the image
Click Place
Resize or move the image if needed
Press Enter or click the checkmark to confirm
Drag and drop an image file into Photoshop
Copy an image from another source
Paste it into Photoshop with Ctrl+V or Cmd+V
Use the Move Tool to reposition the picture
Use Free Transform with Ctrl+T or Cmd+T to resize or rotate the picture