How do I take an object from one photo and place into a second?

The basics aren’t too difficult. The demo below shows these steps:

1. Open the two documents in Photoshop and arrange the side by side. I used the command Window > Arrange > Tile All Vertically. 

2. Use any selection tool that gets you a quick, accurate selection of the subject. I used the Object Selection Tool, but I had to use the basic technique of Shift-selecting to combine multiple selections into one. 

3. Use any technique that transfers the selection to the other document. I used simple drag-and-drop, but you can also use good old copy and paste. 

4. Use the command Edit > Free Transform to match size, position, and rotation.

The difficult part is, as always, in the details. For example, you might make sure you don’t bring the man’s fingers into the other photo because they won’t look like her fingers. Also, because the fingers were wrapped around the subject, when you bring the subject into another picture there are missing pieces where the fingers were holding. You might see other problems around the edges of the subject that make it look fake on the new background. Pros would take the time to fix all that, and put in even more work to match the lighting, shadows, and color balance between the inserted subject and the photo behind it. You might spend one minute moving the subject to the other photo, and a whole hour or more trying to resolve  the visual inconsistencies between each image, and that’s pretty much normal if you want it to look convincing..

For more details on any of these techniques such as how to select an object, or how layers work, you can start with the tutorials built into Photoshop, such as the Learn category of the Home screen. There are many more built-in tutorials available, which you can reach by choosing the command Help > Hands-On Tutorials.