Theme development

Hello, I'm trying to go through the Drupal 8 User Guide.  I've been stuck for a long time, which is probably good since I learned the CMS much better, but I'm about to give up on this one point and thought I'd give the forum a shot.

I have a content type called "panel-image". Within that I have a field with the machine name "field_url", it's a plain Text field that a user can type a URL into. I have created a panel-image piece of content where I entered the url for Google.

I'm now attempting to make a custom template for that content type called node--panel-image.tpl.php.

What I want to do is render the field_url value into my template.

Here is what I have in my node--panel-image.tpl.php file:

Hello,

My question; can I add a secondary menu to every theme, or is it depending on the theme possibilities?

I'm new to drupal. 10 Years ago i developed some website in PHP/MySQL as a hobby.
Now I've more time again and i would like to get back into web design. Nowadays there are very nice CM systems and I prefer to learn drupal. So I’ve watched and read a lot tutorials.

How to add the registration page link in the user account menu that will only be visible to non logged in users. I tried to find the registration page in admin but I couldn't find it.

Thanks

Hi, 

Working with a bootstrap subtheme, gulp and sass.  I have edited my scss files, and compiled the scss to two css files if I use the minifed version in my library:

global-styling:
  css:
    theme:
      css/style.min.css: { minified: true }

The changes are not displayed in my site (but they are in the minified file).

If I change my library to: 

global-styling:
  css:
    theme:
      css/style.css: {}

The changes are displayed. 

I am using drupal 8, I created Recent content block for the sidebar, It's showing both the recent pages and articles, how can I make it show only the latest articles? I tried the block configuration to restrict the basic pages, but The sidebar disappeared completely. 

Thanks