How to add modal box in your application

Code is below 

 <div class="modal" id="popUpWindow">

    <div class="modal-dialog">

      <div class="modal-content">

        <!-- header -->

        <div class="modal-header" >

          <p align ="center">Assign Ticket To Progrmmer</p> <br>

<form action="function.php?id=<?php echo $id; ?>" id=myform" method="post" enctype="multipart/form-data">

<select name="progrmaer" id="progrmaer"   class="form-control">

<?php

  

   $sqlprogramer = "select * from sahakaar_user where company = 'Programmer'";

  $rowprogramer = mysql_query($sqlprogramer);

  while($data = mysql_fetch_array($rowprogramer))

  { ?>

<option value="<?php echo $data['name'];  ?>"><?php echo $data['name'];  ?></option>

<?php

  

 }

  

 ?>

  

<input type="text"  id="timea" name="timea" class="form-control" placeholder="Aprox Time" value=""/>

 <input type="hidden"  id="asignby" name="asignby" class="form-control" placeholder="Aprox Time" value="<?php echo $_SESSION['name']; ?>"/>

 <br>

 <div align="center">

 <input type="submit" style="background-color:red;color:white; id="assubmit" name="assubmit" value="submit"/>

 </div>

  </form>

        </div>

</div>

        

<div class="modal-footer">

                    

</div>

                

</div>

      </div>

<!-- Trigger/Open The Modal -->

<button data-toggle="modal" data-target="#popUpWindow">Assign  </button>