You need to install the plugin Webnus Portfolio via this article and activate it. Install Plugins Then a new menu will be added to WordPress dashboard panel called Portfolio.
In Portfolio sub menu: Portfolio shows all the posts.
In Portfolio sub menu: Add Portfolio Item, you can add a new post.
In Portfolio sub menu: Portfolio Category, you can set categories.
Webnus Portfolio Options
In Portfolio Options, you can set which style to be shown for next and previous posts navigation. You can also show the Related Works, you need to check its CheckBox.