aspx ten arınmış şekli bunu parçalayarak wordpress entegre edebilirsiniz.
<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title>Ali Karakoç - select box</title>
    <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
    <script type="text/javascript">

        $(document).ready(function () {
            var x = "";
            var y = "";
            $("#x").change(function () {
                x = $("#x").val();
            });

            $("#y").change(function () {
                y = $("#y").val();
                if ($("#y").val() == "" || $("#x").val() == "") {
                    alert("Seçim yapınız.");
                    return false;
                }
                location.href = x + "-" + y + ".htm";
            });
        });

    </script>
</head>
<body>
    <form id="form1">
        X Seçin :
        <select id="x">
            <option value="">seç</option>
            <option value="1">1</option>
            <option value="2">2</option>
            <option value="3">3</option>
            <option value="4">4</option>
            <option value="5">5</option>
        </select>

        Y Seçin : 
        <select id="y">
            <option value="">seç</option>
            <option value="6">6</option>
            <option value="7">7</option>
            <option value="8">8</option>
            <option value="9">9</option>
        </select>
    </form>
</body>
</html>