You already know how to use this component because it changes nothing! All it does is clean up the elements a bit and give it a nice shine. But here's an example anyways:
<fieldset>
<legend>Personal Information</legend>
<form>
<ul>
<li>
<label>First Name</label>
<input type="text" placeholder="Your first name here">
</li>
<li>
<label>Last Name</label>
<input type="text">
</li>
<li>
<label>Email Address</label>
<input type="email" required>
</li>
<li>
<label>Address</label>
<textarea></textarea>
</li>
<li>
<input type="submit">
</li>
</ul>
</form>
</fieldset>