bagaimana cara menambahkan jquery dan css di index.php ?

sudah ditambahkan  dibagian header
<!-- bootstrap time picker -->
    <script src="timepicker/bootstrap-timepicker.min.js"></script>
 
bagian footer
  <!-- Bootstrap time Picker -->
    <link rel="stylesheet" href="plugins/timepicker/bootstrap-timepicker.min.css">
 
 
<script>
      $(function () {
        //Initialize Select2 Elements
        $(".select2").select2();
 
        //Datemask dd/mm/yyyy
        $("#datemask").inputmask("dd/mm/yyyy", {"placeholder": "dd/mm/yyyy"});
        //Datemask2 mm/dd/yyyy
        $("#datemask2").inputmask("mm/dd/yyyy", {"placeholder": "mm/dd/yyyy"});
        //Money Euro
        $("[data-mask]").inputmask();
 
        //Date range picker
        $('#reservation').daterangepicker();
        //Date range picker with time picker
        $('#reservationtime').daterangepicker({timePicker: true, timePickerIncrement: 30, format: 'MM/DD/YYYY h:mm A'});
        //Date range as a button
        $('#daterange-btn').daterangepicker(
            {
              ranges: {
                'Today': [moment(), moment()],
                'Yesterday': [moment().subtract(1, 'days'), moment().subtract(1, 'days')],
                'Last 7 Days': [moment().subtract(6, 'days'), moment()],
                'Last 30 Days': [moment().subtract(29, 'days'), moment()],
                'This Month': [moment().startOf('month'), moment().endOf('month')],
                'Last Month': [moment().subtract(1, 'month').startOf('month'), moment().subtract(1, 'month').endOf('month')]
              },
              startDate: moment().subtract(29, 'days'),
              endDate: moment()
            },
        function (start, end) {
          $('#reportrange span').html(start.format('MMMM D, YYYY') + ' - ' + end.format('MMMM D, YYYY'));
        }
        );
 
        //iCheck for checkbox and radio inputs
        $('input[type="checkbox"].minimal, input[type="radio"].minimal').iCheck({
          checkboxClass: 'icheckbox_minimal-blue',
          radioClass: 'iradio_minimal-blue'
        });
        //Red color scheme for iCheck
        $('input[type="checkbox"].minimal-red, input[type="radio"].minimal-red').iCheck({
          checkboxClass: 'icheckbox_minimal-red',
          radioClass: 'iradio_minimal-red'
        });
        //Flat red color scheme for iCheck
        $('input[type="checkbox"].flat-red, input[type="radio"].flat-red').iCheck({
          checkboxClass: 'icheckbox_flat-green',
          radioClass: 'iradio_flat-green'
        });
 
        //Colorpicker
        $(".my-colorpicker1").colorpicker();
        //color picker with addon
        $(".my-colorpicker2").colorpicker();
 
        //Timepicker
        $(".timepicker").timepicker({
          showInputs: false
        });
      });
    </script>
 
dipanggil di sini 
 
<th scope='row'>Jam Mulai</th><td><input type='text' class='form-control timepicker'  name='i'  placeholder='hh:ii:ss' value='".date('H:i:s')."'></tr>
					 </div>
                    <tr><th scope='row'>Jam Selesai</th><td><input type='text' class='form-control timepicker' name='j' placeholder='hh:ii:ss' value='".date('H:i:s')."'></td></tr></div>