Tag cloud empty?

tags will show only if there are posts associated with them. check this case.

check this tag in sidebar.php:

<?php wp_tag_cloud( $args ); ?>

or something like this

You need to write posts and assign tags to those posts as ryans149 explained.

There is NO wp_tags table, but rather, a set of 3 “term” tables comprise tags and their connections to posts.

See Database Description