How to make the language selection block in the page template

I have developed a Twig page in Drupal 8 to allow visitors to my website to select the language of their choice. I have downloaded all the multilingual contrib modules.

I am faced with two problems:

  1. How to render a block in the middle of my twig's page to display the Language drop-down menu? (I already have a block that displays a pull-down menu language from a contrib module).
  2. The CSS background image that I configured covers one of the Twig fields I wanted to test. How can I change the CSS to make the twig block?