placement of subject on new background

[teach4me]

Hello everyone! I have been trying to practice the extraction technique this weekend. I have done an okay job of extracting people, but when I go to place them on another background I can't get the 2 pictures to mesh. I am trying to place a whole body image of the person on the new background. If I slide the extracted image down to where their feet are off the picture and you can't see them, they look like they belong to the new picture. However, if I try to place the entire extracted image on the new background it looks out of place.

I have been trying to look for tutorials for placing extracted images on new backgrounds, but apparently don't have the right keywords in my search.

Can anyone help me out or point me in the direction to a tutorial that will help me?