center bootstraps nav items

center bootstraps nav items

I add a new class to ul and try to style it with margin: 0 auto and
text-align: center but doesn't work..
<section class="navbar navbar-default">
<ul class="nav navbar-nav">
<li class="active"><a href="index.php">Home</a></li>
<li><a href="venue.php">Venue</a></li>
<li><a href="schedule.php">Schedule</a></li>
<li class="dropdown">
<a href="#" class="dropdown-toggle"
data-toggle="dropdown">Artists <span
class="caret"></span></a>
<ul class="dropdown-menu" role="menu"
aria-labelledby="dropdownMenu">
<li><a href="artists.php" tabindex="-1">All
Artists</a></li>
<li class="divider"></li>
<li><a href="#" tabindex="-1">1st</a></li>
<li><a href="#" tabindex="-1">2nd</a></li>
<li><a href="#" tabindex="-1">3rd</a></li>
</ul>
</li>
<li><a href="Register.php">Register</a></li>
</ul>
</section>