understanding categories and pages? -not

I don’t understand.

Originally I thought I make a category then make a page for that category then connect the page to the category and I would be able to see it.

Well I did find a post that explained what pages were and were not, and that I couldn’t connect pages to Categories.

I read somewhere that a category would not show up in the side menu unless it has content in it. I created 7 categorise. Currently the only category showing up in the side menu (in my new/first install). is the one called Home.
https://tammymitchell.com/clanmowat/

I’m just having a real hard time understanding how to get any content on the wordpress site I’m making. I don’t seem to understand it at all.
It’s odd, because I can install scripts (I just installed the entire TNG script and the plugin for it) But I can’t seem to understand how to put my content on to the site.

Can someone explain to me in simple terms what I should be doing?
Is it that Pages are what I really want to create, instead of categories? The only part of the site I want as an active blog is the section called Mowat Family Blogs, where I was hoping anyone could leave a post for other’s too read.. The rest of the site for the most part should just contain stagnant content..