Generating a post/input form on the same page during a button onClick event?

[ben_dajao]

<td id="table-cell"><label> Travelers: </label></td>
<td id="table-cell"><input type="button" onClick="" name="" value="Add Traveler" /></td>

I need an ajax/js function that will generate an input form to be filled up when the Add Traveler button is clicked. (not open a new window but generate it on thesame page)
So, I want to generate this form when the button is clicked:

<?php
<form name="addto_names" action="" method="POST">
  <table>
	<tr><td> Travel Order No. :</td></tr>
            <td><input type="text" name="to_no" value=""></td>
        <tr><td> Employee Id :</td></tr>
            <td><input type="text" name="empid" value=""></td>
        <tr><td> Employee or Student :</td></tr>
            <td><select name="nametype">
                <option>Employee</option>
                <option>Student</option>
                </select>
            </td>
        <tr><td > Traveler Name :</td></tr>
            <td><input type="text" name="to_name" value=""></td>
        <td><input type="hidden" name="lastuser" value="<?php echo              $_SESSION['username']; ?>"
   </table>
</form>
?>