Pick up and carry objects in third person.

I'm working on a simple game with third person view. I want my character to pick objects off the ground and carry them away. When he pick up the object, it need to show as he's holding it. For example, if there's a barrel, he needs to be able to pick it up. How do I do this?

(I apologize if the question is unclear. I'll describe more if needed. I looked everywhere for the answer but couldn't find. Thanks in advance.)