ต้องการเพิ่ม pop-up alert และ block date ใช้คำสั่งอะไรค่ะ

<label class="sdate" style="padding-top:10px"><strong> Check in Date : 
                 </strong> 
                <input type="text" value="<?php if (!$_GET['sdate_tour_pkg']) echo date("m/d/Y"); else $_GET['sdate_tour_pkg'];?>" id="sdate_tour_pkg" name="sdate_tour_pkg" style="width:100px; margin-right:15px" readonly>
                <!--<label class="sdate">  <input type="hidden" value="<?php //echo getdate('yy-mm-dd')?>" id="edate"> -->
                </label> 
            </div>

            <div class="booking-summary" style="width:225px; height:auto; margin-right:0px;  ">
                <label class="sdate" style="padding-top:10px"><strong> Check out Date :
                 </strong> 
                  <input type="text" value="<?php if (!$_GET['edate_tour_pkg']) echo yeopackagemaxdate(date("m/d/Y"),$val_length); else $_GET['edate_tour_pkg']?>" id="edate_tour_pkg" name="edate_tour_pkg" style=" width:100px" readonly>
                </label> 
            </div>