How to start?

Does anyone have instructions on how to start?

I have a bare UNA installation in front of me and just can't get any further.

Is there no demo site?

A simple and simple website where you can understand everything?

At the moment the system and concept are not opening up to me.

For example, I go to "Pages" -> "Select Page" -> "Homepage".

Then I see the main homepage.

If I add "Add Blocks" -> "System" -> "Create Post (Visible for Anyone)" and update the start page, then "Create Post" does not appear. Why?

If I go to "Navigation" -> "Homepage Menu" and add a new item "Home" with "Add New Item", how should I know what the url to index.php or any other page is?

If I look at the item "Persons", then under Url it says "page.php? I = persons-home".

Where does "Persons Home" come from? Where is this page? Where does the abbreviation "persons-home" come from?

Why does the new navigation item "Home" appear on the start page to the right of People and not below?

Can anyone help me please. I don't understand the system and the logic behind it.