how to interact particular part of object in croquet

hi friends,

           i am new in croquet....
           how to interact particular part of object in croquet

   example:

                 human  is one object

                 it has head,hand,leg.....

                 i can interact total object(human)...

                  but i can't interact particular part of human(head,hand,leg)

                                                               help
me...............................