The multilingual setup is not theme specific, it’s pretty much a generic process.
To translate the internal theme text labels simply translate the PO/MO files found in the ‘languages’ directory, then save the new files as your new language locale is called, for example DE_de or ES_es…
There are plenty of tutorials you can find online…

https://doc.osclass.org/Translating_and_editing_language_files_(.po_and_.mo)

Once you have your new files (PO MO) you can change the active language in your Dashboard and your theme will be loaded in your new language.

To translate your Posts/Pages you need a translating plugin like qTranslate, Polylang or WPML.
Let me know if you have any issues along the way.