Module development and code questions

Hi :) I'm somewhat of a newbie... So please bare with me.

I want to add feeds of employee directory to my drupal 10 site.  When I add them, it creates a content for each employee.  I tried searching for this, couldn't find anything here or on the web.  

I don't want the content page to show 1000+ employees, what can I do?  Anyone?

I am opening a simple dialog box from Ajax, using the following code-

var exportActionDialog = Dialog.ajax({
dialog: dialogSettings,
dialogType: 'modal',
type: 'POST',
url: '/web/admin/crm/export-dialog',
data: { whatever: 'itworking' },
progress: { type: 'throbber'}
});
exportActionDialog.execute();

The dialog actually opens successfully and displays the form associated with the url.

But I can't get the value of the whatever post variable.

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: