<select id='select1' name='select1' onchange='processSelection();'>
  <option value='1'>Value 1</option>
  <option value='2'>Value 2</option>
  <option value='3'>Value 3</option>
</select>

<div id='textboxContainer'>
  <input type='text' id='text1' name='text1' />
  <input type='text' id='text2' name='text2' />
</div>