Drupal 8.x

I am using drupal 8.9.10
I have a content type with several text field, and a file field too.

My problem is: 
- I have to call an external web service. 
- This web service receives a file and returns it with a verification code.
- I have to add this file to the file field
 and finally save all the content

I am a beginner in drupal, I have been looking at tutorial to create custom modules and I don't know how to develope this. 

I don't know if it is necessary to create a module or create a custom field

I run my farm page on Drupal.  I was using Drupal 7, but I created a Drupal 8 replacement page, using composer to install.

I self host in a dedicated VM with a reverse proxy to manage multiple URL's on my static forward facing IP.

Now that I have updated my reverse proxy to point one of the URL's to the VM I am running the Drupal 8 page on, I need my pages to map to the URL as opposed to the IP.

When I login, the address changes from URL to IP and I get "not authorized to access".  I edit the address to put the URL in and it connects me...but...

I want to add a user field on a content type, which is quite simple. But I get the username and I want the real Name. Also it should be possible to add several users, comma separated shown. Does anybody have a hint?

Hello,

When I paste any url from my website in facebook, I like the logo to display as preview. But I see a different image from the site is being displayed in facebook preview. 

Installed Meta Tags and Token. 

Global configuration of meta tags, I added the tokens under open graph: title, image url, description. 

When I view the mark up, I see this every page:

I have one content type (article) and that content type has multiple taxonomy terms to differentiate content, so I have only articles, then i tag each one as News, About, Artists and more.

I want to create a view which shows just the one single newest post for each taxonomy term. So if I have 5 tax terms, I want to display 5 posts, the newest of each tax term.

I see that I can do the 5 newest posts for the article content type, but not how to make it one of each tax term.

I'm trying to change Bootstrap colors, but it doesn't work. Here is the error message :