Copying one blender creation to another...

So, I’ve made my first 3d model, its of a torso,legs, and arms. Now my friend has made some feet, and hands, and a head. How can i copy one into the other??

Shift+F1 - append http://wiki.blender.org/index.php/Doc:Manual/Data_System/Linked_Libraries

So I got the hands and feet loaded, but now I can’t connect them to the body because I can only edit the body, or the hands and feet at a time.

Select the meshes and push control + J to ‘join’ the meshes into one object.