using WWW to upload prefabs/game objects in webplayer... help

Hello, this is my code: what I'd like to achieve is uploading a prefab/gameobject in my scene in the webplayer... is it a good solution? because actually it returns me some errors.. what should I call after having uploaded a prefab/gameobject.

Many thanks.

function buttonwww () {

    var www = new WWW("http://localhost/Prefabs/PetrieRoom.prefab");
    yield www;
    print(www.bytes);
    AND THEN!?!! Instantiate(WHAT?)

}

function OnGUI () {

if(GUI.Button(Rect(25,25,100,30),"Load www" )) {

buttonwww(); }

}