$(window).scroll(function() {
        if ($(this).scrollTop() > 257) { //I just used 200 for testing
            $(".wp-facebook").css({ "position": "fixed", "top": "10px", "right": "42px" });
        } else {
            $(".wp-facebook").css({ "position": "absolute", "top": "90px",  "right": "20px" }); //same here
        }
    });