how do i copy a selection area and then paste it

I put a picture and some text below it and now i want to copy it and paste it below it. The problem is i dont know how to select an area and copy it.

never mind i found it out…

Can you tell me how? I want to take the bottom half of an image and raise it higher.

It seems, no matter what I do, I only get “a fist” cursor once I enter the area of the image.