Edit in JSFiddle

$(document).ready(function() {
  $('select').select2({
    placeholder:'Select a state',
  });
});

<select name="brand">
  <option value ="volvo">Volvo</option>
  <option value ="saab">Saab</option>
  <option value="opel">Opel</option>
  <option value="audi">Audi</option>
</select>