hide parts of a form until the 1st item is selected

HTML

<form>
<div class='form-row'>
<input type='text' placeholder='Hi im the 1st Row' onclick="document.getElementById('hidden_form').style.display = 'block';">
</div>
<div id='hidden_form' style='display:none;'>
 <div class='form-row'>
 <input type='text' placeholder='Hi im the 2nd Row'>
 </div>
 <div class='form-row'>
 <input type='text' placeholder='Hi im the 3rd Row'>
 </div>
 <div class='form-row'>
 <input type='submit' value='Save Me!'>
 </div>
</div>
</form>

Javascript

document.getElementById('hidden_form').style.display = 'block';