Mark div objects as selected

This is my jsfiddle.

I want to be able to mark div objects as selected. These objects should have a class draggable (red circles).

Also, the selection can be applied to those circles that are inside div area that has a class dropzone.

div.draggable.selected {
    border:4px solid black;
    -moz-border-radius:3px;
    border-radius:3px;
}

JavaScript:

$(window).load(function(){
    $(".draggable").click(function () {
        $(this).toggleClass("selected");
    });
});

How can I do it?