To Get Author information

wordpress code

<?php the_author(); ?>
<?php echo get_avatar( get_the_author_email(), 'size here' ); ?>
<?php echo the_author_link(); ?>
<?php the_author_posts_link(); ?>
<?php the_author_meta( $field, $userID ); ?> 
<?php the_author_meta('twitter'); ?>
<?php the_author_description(); ?>
<?php echo date("D M Y", strtotime(get_userdata(get_current_user_id( ))->user_registered)); ?>


To add more social fields for author:

function my_new_contactmethods( $contactmethods ) {
// Add Twitter
$contactmethods['twitter'] = 'Twitter';
//add Facebook
$contactmethods['facebook'] = 'Facebook';
//here can be add more
return $contactmethods;
}
add_filter('user_contactmethods','my_new_contactmethods',10,1);