Set up multilingualism on Joomla 3

You need to set up multilingualism on the site on the Joomla cms. The theme of the design on the site is not broken, everything works steadily. Work has already begun. Specific tasks for you:
1) Finish multilingualization (3 languages)
2) Create pages and menu items (Translations, of course, are available.
3) Show where pages are filled