How to organize, so that when you click on the button, the application form pops up?

Help me to understand.

Picture

<!-- MENU --> ".s_browse_level(0, $browse_sub[2])." <div class='MENU'>".($browse_sub[2]==$sub ? "<img src='$SUB_FOLDER/images/template/knopka.png' alt='Кнопка' />" : "<a href='$SUB_FOLDER/'><img src='$SUB_FOLDER/images/template/knopka.png' alt='Кнопка' /></a>")."</div><!-- End MENU --> 

And this, for example, should pop up)

 Отправить заявку: <p><select> <option>услуги</option> </select> </p> <p><input value='имя'> </p> <p><input value='сайт'> </p> <p><input value='телефон'> </p> <p><textarea>текст сообщения</textarea></p> </div> </div>