Module development and code questions

How beginner user of drupal org can improve in module development and code question?

For Beginner user of the websites, What do he or she understand to applying website well.?

For Beginner web user, Which modules should  he or she study ? 

Thanks drupal.org.

I want to call this function: public function ExtensionList::getName from my controller class in order to get the human name from the machine name. I'm trying to do it like this:

$human_name = \Drupal\Core\ExtensionList::getName('advanced_help');

which isn't working. The error is:

Error: Class "Drupal\Core\ExtensionList" not found in …

Hello,

I have a big problem for adding a  text_format type in a form from Ajax callback.

Exemple : Part in WidgetBase formElement(...) function

$form['zonedev'] = [
  '#type' => 'markup',
  '#markup' => t('<div id="suite"></div>'),
];

Exemple : Ajax Callback

Hi, I am following this youtuve tutorial on how to make a module:
https://www.youtube.com/watch?v=iY8Ve2ZEgFY&list=PLpVC00PAQQxFNDfiXn6LH1...

For some reason when I try to submit my data "Email field" I get an error. outputted the error it says:
 

How should I code to have 'dot navigation' or pager in every box that is shown by tour ? I want my user to go to any tour step/tip at will ... not just 'next'

I have seen progress (like 7 out of 10 etc) added to all tour boxes.

Please let me know how to add clickable dots or page numbers in every step box.

Thanks

Hello

We took over a website from a customer that was built with Drupal 7.64. Now we noticed that there are a few pages in Google that cannot be accessed via the website.

Can someone tell me how I can find these in Drupal and then integrate them into the menu or make them visible?

Is there something like a directory where all pages and their associated status can be seen?

Thank you!