Drupal 8.x

Hi, Drupal 8 programming newbie here, and I need some help please.

I am building a simple custom module, and I am building a custom block following the instructions in this YouTube tutorial: https://www.youtube.com/watch?v=2vEG2p-D_no

The code for my custom block is below, but after installing (and clearing cache), it does not show up in the Custom Block library.  I've triple checked everything, but I am likely missing something.

Thanks in advance:

There is a default form at URL /node/add/article  to create an article. However I want to create another form in another URL which has less fields for creating article. I know I can edit the form display to change the default form, but I want to keep it like this, and create a second form in another page, do I need coding for achieve this ? Or I can change some configuration settings to make this happen?

Example:

Default form fields :

I was recently tossed into the deep end of Drupal after our Drupal developer left. Not knowing Drupal, or its terminology, makes it difficult to search the forums and documentation for answers. So bare with me.

I'm trying to take a module that he created, and create a scaled down version. I created a new webform using his original as a template, only keeping the elements we still need. One of the elements is Hidden. This is a calculated value based on what was entered in the other elements. The webform functions correctly and data is saved when the form is submitted.

I have view that displays the body field of all published instances of a content type, one per page. Right now we use the pager to switch between nodes but I would like to replace it with horizontal tabs.

My question is quite simple: is it possible to make a subtheme of the eStore template ?

eStore is a subtheme of Bootstrap itself.

• I renamed the files estore.info.yml and estore.libraries.yml by renaming these files, for example, mysubtheme.info.yml and mysubtheme.libraries.yml;
• In these files, I renamed all "estore" parameters to "mysubtheme";
• "estore" is taken up as the basic theme;
• I cleaned all the caches;
• I made an update.php.

It seems that the problem is in the file "mysubtheme.info.yml":

How can I work with responsive image style especially with themes as bootstrap which is

mobile first?

The documentation about responsive image style is very poor...

Thanks.