Appearance - Menu - Categories - Select categories and add to menu.
Wordpress is one of the most simplest CMS where you can create the best website with minimal coding skills.
How to select category in wordpress?
It is to simple firstly go to your dashboard. Click on posts and then under the add new you see categories option. Click on it enter further details and click on add new category.
WordPress
is free of cost. It's open-source, meaning all of its codes are
accessible and customizable by anyone willing to do so and it comes
with various themes and plugins which are also suitable to ecommerce
store also.
I recommend to search video tutorials in Youtube. For example this: https://www.youtube.com/watch?v=ZhWffmye6H8.
If you don't have any skills in WP and coding I can recommend to use ready-made template for website creation. For example I created great website for biker club with this template https://www.templatemonster.com/category/biker-club-wordpress-themes/ design and functionality are great. On this website you can find theme for website for any niche.