I posted 2 articles about C64 themes and it is listed in a new c64 category (also visible with the tag #c64) and they are the only articles in this category. In general, all articles are automatically visible as https://steemit.com/trending/name, where name is a tag. Your posting is listed on a trending page for each tag you use in the tags line below your posting box. This posting uses the following tags:
#steem #steemit #tags #trending #foobarcategory
As you can see if you click the "foobarcategory", only this article is in the trending page for this tag. Note: If you write or edit an article, all hashtags you use in the article, are collected automatically in your list of hashwords in the hastags line below your article.