using function

using function

i want to run a function like " message" :

message( function (  ui  ) {
       ui. box.addClass("msg1");
} );

the message function performs the following:

1. var box = $("<div>message</div>").appendTo($("body"));
2. points to  box with   ui. box

how is the behind code ?
how do i make the  ui. box part ? :/