Please: more help after installing second language

After consultation with Gabor I now understand the following (please correct me if I am wrong):

1. I you want a website in three languages, say: English, Dutch and Russian, you have to start installing in one of these languages
2. the language you choose for installing the site, will become your "Default language"
3. if your "default language" is English, you have to go to admin/modules and switch on "Language", if your "Default language" is not English, the module "Language" was switched on automagically.
4. after installing the website, please go to admin/config/regional/language and choose the additional languages you need
5. after installing multiple languages (or if you installed Drupal with one non-English language) by default the modules "Language" and "Interface Translation" are switched on, "Content translation" is not (see admin/modules)
6. if you want only one user interface language, not being English, you have to leave the module "Interface Translation" switched on (if you switch it off, the user interface language will be English) and indicate the language for your user interface at: admin/config/regional/language/detection in the first block that says: "User interface language detection"
7. take care: even if you switch off the module "Interface Translation", on the page admin/config/regional/language/detection the first block about "User interface language detection" will show up, even though it does nothing
8. if you want content pages be translatable, you have to switch on the module "Content translation"
9. after switching on the module "Content translation", you can (or actually "have to") change the settings per content type at (for example): admin/structure/types/manage/article
10. and after that you go to the page at: admin/config/regional/content-language and indicate which fields need to be translatable.
11. if you add fields to a content type later, during the procedure of defining the field you will be prompted if the field needs to be translatable

The text on the Language page could actually be depending on which other core modules are enabled.

At least the Language module is switched on, or else the user would not see this page (would she?)

For example:
===============================
Interface translation: off
Content translation: off

With multiple languages enabled, registered users may select their preferred language and authors can assign a specific language to content. The selection of what language is used to display page elements is made depending on the detection menthod settings in the Detection and Selection tab.

[show only if multiple languages are enabled]

Your default language is: [Default language]. If you want to change this, please visit the[link to admin/config/regional/settings]Regional Settings[/link] page

If you want the user interface to be available in multiple languages, please switch on the "Interface translation" module on the [link to module page]module page[/link].

If you want to have translatable content, please switch on the "Content translation" module on the [link to module page]module page[/link].
================================
Interface translation: on
Content translation: off

With multiple languages enabled, registered users may select their preferred language and authors can assign a specific language to content. The selection of what language is used to display page elements is made depending on the detection menthod settings in the Detection and Selection tab.

[show only if multiple languages are enabled]

Your default language is: [Default language]. If you want to change this, please visit the[link to admin/config/regional/settings]Regional Settings[/link] page

You can configure the interface language settings on the languages [link to admin/config/regional/language/detection]Detention and Selection[/link] page

If you want to have translatable content, please switch on the "Content translation" module on the [link to module page]module page[/link].

================================
Interface translation: off
Content translation: on

With multiple languages enabled, registered users may select their preferred language and authors can assign a specific language to content. The selection of what language is used to display page elements is made depending on the detection menthod settings in the Detection and Selection tab.

[show only if multiple languages are enabled]

Your default language is: [Default language]. If you want to change this, please visit the[link to admin/config/regional/settings]Regional Settings[/link] page

If you want the user interface to be available in multiple languages, please switch on the "Interface translation" module on the [link to module page]module page[/link].

Content translation configuration is switched on. You can make content types translatable through the settings in each content type and additionally at the [link to admin/config/regional/content-language]Content language settings[/link] page

================================
Interface translation: on
Content translation: on

With multiple languages enabled, registered users may select their preferred language and authors can assign a specific language to content. The selection of what language is used to display page elements is made depending on the detection menthod settings in the Detection and Selection tab.

[show only if multiple languages are enabled]

Your default language is: [Default language]. If you want to change this, please visit the[link to admin/config/regional/settings]Regional Settings[/link] page

You can configure the interface language settings on the languages [link to admin/config/regional/language/detection]Detention and Selection[/link] page

Content translation configuration is switched on. You can make content types translatable through the settings in each content type and additionally at the [link to admin/config/regional/content-language]Content language settings[/link] page

Also add the text (visible when multiple languages are enabled):

Reordering the languages here will reorder the languages as they are shown in the "language selection" widget when create/edit content.

I do not use Drupal anymore. Do what you think is good.