word press theme Dev basic things

1. get the post categories…

//$categories = get_categories(); //all category
$categories = get_the_category($post->ID); //post category
if($categories !=null){
    foreach($categories as $category) {
       echo '<a href="' . get_category_link($category->term_id) . '" class="term-link">' . $category->name . '</a> ';
    }
}

2. get the date ….

<?php echo get_the_date('j M,Y'); ?>

3.get thumbnail….

<?php echo wp_get_attachment_url(get_post_thumbnail_id());?>