[jQuery] Help with $.ajax function

Hi,
I'm a little unsure on how the $.ajax function works in terms of
returning a value. I would like the below to insert the returned
values into a div..... but i'm unsure what would go into the t()
function.
$.ajax({
type: "POST",
url: "autocomplete.php",
data: "typing=1",
success: function t() {
//insert return value into a div element
}
});
Thanks