millerguide on "Change text of comment form "Post Comment" button."

Hello,
I would like to change the text of "Post Comment" on the comment form button. I am not sure where to do this. Here is my comment.php code so far:

?>
<?php if ( have_comments() ) : ?>

<?php echo apply_filters( 'comment_separator', '<hr class="featurette-divider '.current_filter().'">' ); ?>

<?php endif; ?>

<div id="comments" class="comments-area">

<?php
$args = array(
'title_reply' => __( '您的评语 Your Review', 'customizr' ),
);

comment_form($args);

?>

<?php if ( have_comments() ) : ?>

<?php do_action ( '__comment' );?>

<?php endif; // have_comments() ?>

</div><!-- #comments .comments-area -->