If WPML Plugin installed activated, a language switcher will appear on your footer (if you have placed there a “(Contrast) Footer Text” widget and checked “Display WPML language switcher?” box.

For mobile devices, you can add “(Contrast) WPML Language Switcher” widget to “Mobile Side Menu” sidebar.

What about my sidebars? Also multilingual?

Yes, new sidebars will automatically appear on your “Appearance > Widgets” page. Will be named like “Side Menu (Deutsch)“, that means you can place whatever you want there to customize your sidebars.