Enabling Multilingual support for Content
In this step, we'll select which types of content need to be translated. Navigate to /admin/content/types and select a content type that you will want translated. Under "Workflow settings" select Multilingual support - Enabled, with translation.

Once you make contents multilingual, you can translate them using the "Translate" tab or the Translation Dashboard.
Repeat for all content types that you will want translated.
Note: the Setup Checklist page will notify you about content types that don't have multilingual support enabled.

Kommentare
Big big problem...
Immediately after doing what above, I got the following responsa from my site:
The page cannot be found
The page you are looking for might have been removed, had its name changed, or is temporarily unavailable.
Please try the following:
Make sure that the Web site address displayed in the address bar of your browser is spelled and formatted correctly.
If you reached this page by clicking a link, contact the Web site administrator to alert them that the link is incorrectly formatted.
Click the Back button to try another link.
HTTP Error 404 - File or directory not found.
Internet Information Services (IIS)
Technical Information (for support personnel)
Go to Microsoft Product Support Services and perform a title search for the words HTTP and 404.
Open IIS Help, which is accessible in IIS Manager (inetmgr), and search for topics titled Web Site Setup, Common Administrative Tasks, and About Custom Error Messages.