[jQuery] update a select field by ajax

[jQuery] update a select field by ajax


Hi
that is the first time I use the Ajax functionality of JQuery and I
face so many problem. I meant that to update my select field by Ajax I
need to do it by this way:
$("#myId").change(function () {
    $.ajax({
        url: "ajaxCallback.php",
        cache: true,
        type: "GET",
        data: "param=toto",
        dataType: "html"
    });
});
My php page display the complete field so:
<select name="myId" onchange="load_select()" class="disable"
id="myId">
<option value="1">Option 1</option><option value="2">option 2</option>
</select>
What could I change to update the field with the one wich has been
generated please?