How to get particular user data in Wordpress?

<?php $user_info = get_userdata(1);
      $username = $user_info->user_login;
      $first_name = $user_info->first_name;
      $last_name = $user_info->last_name;
      echo "$first_name $last_name logs into her WordPress site with the user name of $username.";
?>

 You can go to http://codex.wordpress.org/Function_Reference/  for more detail....