You’ll want to add breadcrumbs to your single posts and pages. Breadcrumbs are the links, usually above the title post, that look like “Home > Articles > WordPress SEO”. They are good for two things:
They allow your users to easily navigate your site.
They allow search engines to determine the structure of your site more easily.
These breadcrumbs should link back to the homepage, and the category the post is in. If the post is in multiple categories it should pick one. For that to work, adapt single.php and page.php in your theme, and use the breadcrumbs from my WordPress SEO plugin. You find the settings for the breadcrumbs in the SEO → Internal Links settings page