how do i install J Query select2? : i have been trying to install and use select2 for my drop-down but i just cant get it to work, i tried following what is documented here: http://stackoverflow.com/questions/36132875/how-to-use-select2-bootstrap but still got no luck 
here is my code:

    <link rel="stylesheet" type="text/css" href="https://cdnjs.cloudflare.com/ajax/libs/select2/4.0.3/css/select2.css">
    <link rel="stylesheet" type="text/css" href="https://cdnjs.cloudflare.com/ajax/libs/select2-bootstrap-css/1.4.6/select2-bootstrap.css">
    <link rel="stylesheet" type="text/css" href="https://cdnjs.cloudflare.com/ajax/libs/select2/4.0.3/css/select2.css">

    <body>
    <script>
    
    $("#disease").select2({
      allowClear:true,
      placeholder: 'Search for a disease'
    });
    </script>
    <select id="disease" style="width: 40%;  position: relative;top: 220px; left: 182px; " name="tdisease" >
                            <option value="">Select Disease</option>
                             <?php while ($row=$result->fetch_array(MYSQLI_ASSOC)) { ?>
                            <option value="<?php echo $row['ICD10']?>"><?php echo $row['diagnosis'];?> </option> 
                      <?php } ?> 
                         </select>

    </body>


